From fd41ff9b36d941037105a0a9b1bdceeeac2dad08 Mon Sep 17 00:00:00 2001 From: Tobias Powalowski Date: Sat, 24 Jun 2017 07:52:30 +0000 Subject: [PATCH] bump to latest version --- ...ck-to-grow-up-to-address-space-limit.patch | 45 - ...x-new-crash-in-unmapped_area_topdown.patch | 47 - ...-larger-stack-guard-gap-between-vmas.patch | 883 ------------------ 3 files changed, 975 deletions(-) delete mode 100644 CVE-2017-1000364.fixup.allow-stack-to-grow-up-to-address-space-limit.patch delete mode 100644 CVE-2017-1000364.mm-fix-new-crash-in-unmapped_area_topdown.patch delete mode 100644 CVE-2017-1000364.mm-larger-stack-guard-gap-between-vmas.patch diff --git a/CVE-2017-1000364.fixup.allow-stack-to-grow-up-to-address-space-limit.patch b/CVE-2017-1000364.fixup.allow-stack-to-grow-up-to-address-space-limit.patch deleted file mode 100644 index 58ec52f..0000000 --- a/CVE-2017-1000364.fixup.allow-stack-to-grow-up-to-address-space-limit.patch +++ /dev/null @@ -1,45 +0,0 @@ -From bd726c90b6b8ce87602208701b208a208e6d5600 Mon Sep 17 00:00:00 2001 -From: Helge Deller -Date: Mon, 19 Jun 2017 17:34:05 +0200 -Subject: [PATCH] Allow stack to grow up to address space limit - -Fix expand_upwards() on architectures with an upward-growing stack (parisc, -metag and partly IA-64) to allow the stack to reliably grow exactly up to -the address space limit given by TASK_SIZE. - -Signed-off-by: Helge Deller -Acked-by: Hugh Dickins -Signed-off-by: Linus Torvalds ---- - mm/mmap.c | 13 ++++++++----- - 1 file changed, 8 insertions(+), 5 deletions(-) - -diff --git a/mm/mmap.c b/mm/mmap.c -index 290b77d9a01e0..a5e3dcd75e79f 100644 ---- a/mm/mmap.c -+++ b/mm/mmap.c -@@ -2230,16 +2230,19 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) - if (!(vma->vm_flags & VM_GROWSUP)) - return -EFAULT; - -- /* Guard against wrapping around to address 0. */ -+ /* Guard against exceeding limits of the address space. */ - address &= PAGE_MASK; -- address += PAGE_SIZE; -- if (!address) -+ if (address >= TASK_SIZE) - return -ENOMEM; -+ address += PAGE_SIZE; - - /* Enforce stack_guard_gap */ - gap_addr = address + stack_guard_gap; -- if (gap_addr < address) -- return -ENOMEM; -+ -+ /* Guard against overflow */ -+ if (gap_addr < address || gap_addr > TASK_SIZE) -+ gap_addr = TASK_SIZE; -+ - next = vma->vm_next; - if (next && next->vm_start < gap_addr) { - if (!(next->vm_flags & VM_GROWSUP)) diff --git a/CVE-2017-1000364.mm-fix-new-crash-in-unmapped_area_topdown.patch b/CVE-2017-1000364.mm-fix-new-crash-in-unmapped_area_topdown.patch deleted file mode 100644 index 25fc3f5..0000000 --- a/CVE-2017-1000364.mm-fix-new-crash-in-unmapped_area_topdown.patch +++ /dev/null @@ -1,47 +0,0 @@ -From f4cb767d76cf7ee72f97dd76f6cfa6c76a5edc89 Mon Sep 17 00:00:00 2001 -From: Hugh Dickins -Date: Tue, 20 Jun 2017 02:10:44 -0700 -Subject: [PATCH] mm: fix new crash in unmapped_area_topdown() - -Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of -mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the -end of unmapped_area_topdown(). Linus points out how MAP_FIXED -(which does not have to respect our stack guard gap intentions) -could result in gap_end below gap_start there. Fix that, and -the similar case in its alternative, unmapped_area(). - -Cc: stable@vger.kernel.org -Fixes: 1be7107fbe18 ("mm: larger stack guard gap, between vmas") -Reported-by: Dave Jones -Debugged-by: Linus Torvalds -Signed-off-by: Hugh Dickins -Acked-by: Michal Hocko -Signed-off-by: Linus Torvalds ---- - mm/mmap.c | 6 ++++-- - 1 file changed, 4 insertions(+), 2 deletions(-) - -diff --git a/mm/mmap.c b/mm/mmap.c -index 8e07976d5e477..290b77d9a01e0 100644 ---- a/mm/mmap.c -+++ b/mm/mmap.c -@@ -1817,7 +1817,8 @@ unsigned long unmapped_area(struct vm_unmapped_area_info *info) - /* Check if current node has a suitable gap */ - if (gap_start > high_limit) - return -ENOMEM; -- if (gap_end >= low_limit && gap_end - gap_start >= length) -+ if (gap_end >= low_limit && -+ gap_end > gap_start && gap_end - gap_start >= length) - goto found; - - /* Visit right subtree if it looks promising */ -@@ -1920,7 +1921,8 @@ unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) - gap_end = vm_start_gap(vma); - if (gap_end < low_limit) - return -ENOMEM; -- if (gap_start <= high_limit && gap_end - gap_start >= length) -+ if (gap_start <= high_limit && -+ gap_end > gap_start && gap_end - gap_start >= length) - goto found; - - /* Visit left subtree if it looks promising */ diff --git a/CVE-2017-1000364.mm-larger-stack-guard-gap-between-vmas.patch b/CVE-2017-1000364.mm-larger-stack-guard-gap-between-vmas.patch deleted file mode 100644 index 681fec4..0000000 --- a/CVE-2017-1000364.mm-larger-stack-guard-gap-between-vmas.patch +++ /dev/null @@ -1,883 +0,0 @@ -From: Hugh Dickins -Date: Mon, 19 Jun 2017 04:03:24 -0700 -Subject: mm: larger stack guard gap, between vmas -Origin: https://git.kernel.org/linus/1be7107fbe18eed3e319a6c3e83c78254b693acb - -Stack guard page is a useful feature to reduce a risk of stack smashing -into a different mapping. We have been using a single page gap which -is sufficient to prevent having stack adjacent to a different mapping. -But this seems to be insufficient in the light of the stack usage in -userspace. E.g. glibc uses as large as 64kB alloca() in many commonly -used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] -which is 256kB or stack strings with MAX_ARG_STRLEN. - -This will become especially dangerous for suid binaries and the default -no limit for the stack size limit because those applications can be -tricked to consume a large portion of the stack and a single glibc call -could jump over the guard page. These attacks are not theoretical, -unfortunatelly. - -Make those attacks less probable by increasing the stack guard gap -to 1MB (on systems with 4k pages; but make it depend on the page size -because systems with larger base pages might cap stack allocations in -the PAGE_SIZE units) which should cover larger alloca() and VLA stack -allocations. It is obviously not a full fix because the problem is -somehow inherent, but it should reduce attack space a lot. - -One could argue that the gap size should be configurable from userspace, -but that can be done later when somebody finds that the new 1MB is wrong -for some special case applications. For now, add a kernel command line -option (stack_guard_gap) to specify the stack gap size (in page units). - -Implementation wise, first delete all the old code for stack guard page: -because although we could get away with accounting one extra page in a -stack vma, accounting a larger gap can break userspace - case in point, -a program run with "ulimit -S -v 20000" failed when the 1MB gap was -counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK -and strict non-overcommit mode. - -Instead of keeping gap inside the stack vma, maintain the stack guard -gap as a gap between vmas: using vm_start_gap() in place of vm_start -(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few -places which need to respect the gap - mainly arch_get_unmapped_area(), -and and the vma tree's subtree_gap support for that. - -Original-patch-by: Oleg Nesterov -Original-patch-by: Michal Hocko -Signed-off-by: Hugh Dickins -Acked-by: Michal Hocko -Tested-by: Helge Deller # parisc -Signed-off-by: Linus Torvalds -[bwh: Backported to 4.11: adjust context] ---- - Documentation/admin-guide/kernel-parameters.txt | 7 ++ - arch/arc/mm/mmap.c | 2 +- - arch/arm/mm/mmap.c | 4 +- - arch/frv/mm/elf-fdpic.c | 2 +- - arch/mips/mm/mmap.c | 2 +- - arch/parisc/kernel/sys_parisc.c | 15 ++- - arch/powerpc/mm/hugetlbpage-radix.c | 2 +- - arch/powerpc/mm/mmap.c | 4 +- - arch/powerpc/mm/slice.c | 2 +- - arch/s390/mm/mmap.c | 4 +- - arch/sh/mm/mmap.c | 4 +- - arch/sparc/kernel/sys_sparc_64.c | 4 +- - arch/sparc/mm/hugetlbpage.c | 2 +- - arch/tile/mm/hugetlbpage.c | 2 +- - arch/x86/kernel/sys_x86_64.c | 4 +- - arch/x86/mm/hugetlbpage.c | 2 +- - arch/xtensa/kernel/syscall.c | 2 +- - fs/hugetlbfs/inode.c | 2 +- - fs/proc/task_mmu.c | 4 - - include/linux/mm.h | 53 ++++----- - mm/gup.c | 5 - - mm/memory.c | 38 ------ - mm/mmap.c | 149 ++++++++++++++---------- - 23 files changed, 152 insertions(+), 163 deletions(-) - ---- a/Documentation/admin-guide/kernel-parameters.txt -+++ b/Documentation/admin-guide/kernel-parameters.txt -@@ -3779,6 +3779,13 @@ - spia_pedr= - spia_peddr= - -+ stack_guard_gap= [MM] -+ override the default stack gap protection. The value -+ is in page units and it defines how many pages prior -+ to (for stacks growing down) resp. after (for stacks -+ growing up) the main stack are reserved for no other -+ mapping. Default value is 256 pages. -+ - stacktrace [FTRACE] - Enabled the stack tracer on boot up. - ---- a/arch/arc/mm/mmap.c -+++ b/arch/arc/mm/mmap.c -@@ -65,7 +65,7 @@ arch_get_unmapped_area(struct file *filp - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/arm/mm/mmap.c -+++ b/arch/arm/mm/mmap.c -@@ -90,7 +90,7 @@ arch_get_unmapped_area(struct file *filp - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -141,7 +141,7 @@ arch_get_unmapped_area_topdown(struct fi - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/frv/mm/elf-fdpic.c -+++ b/arch/frv/mm/elf-fdpic.c -@@ -75,7 +75,7 @@ unsigned long arch_get_unmapped_area(str - addr = PAGE_ALIGN(addr); - vma = find_vma(current->mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - goto success; - } - ---- a/arch/mips/mm/mmap.c -+++ b/arch/mips/mm/mmap.c -@@ -93,7 +93,7 @@ static unsigned long arch_get_unmapped_a - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/parisc/kernel/sys_parisc.c -+++ b/arch/parisc/kernel/sys_parisc.c -@@ -90,7 +90,7 @@ unsigned long arch_get_unmapped_area(str - unsigned long len, unsigned long pgoff, unsigned long flags) - { - struct mm_struct *mm = current->mm; -- struct vm_area_struct *vma; -+ struct vm_area_struct *vma, *prev; - unsigned long task_size = TASK_SIZE; - int do_color_align, last_mmap; - struct vm_unmapped_area_info info; -@@ -117,9 +117,10 @@ unsigned long arch_get_unmapped_area(str - else - addr = PAGE_ALIGN(addr); - -- vma = find_vma(mm, addr); -+ vma = find_vma_prev(mm, addr, &prev); - if (task_size - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma)) && -+ (!prev || addr >= vm_end_gap(prev))) - goto found_addr; - } - -@@ -143,7 +144,7 @@ arch_get_unmapped_area_topdown(struct fi - const unsigned long len, const unsigned long pgoff, - const unsigned long flags) - { -- struct vm_area_struct *vma; -+ struct vm_area_struct *vma, *prev; - struct mm_struct *mm = current->mm; - unsigned long addr = addr0; - int do_color_align, last_mmap; -@@ -177,9 +178,11 @@ arch_get_unmapped_area_topdown(struct fi - addr = COLOR_ALIGN(addr, last_mmap, pgoff); - else - addr = PAGE_ALIGN(addr); -- vma = find_vma(mm, addr); -+ -+ vma = find_vma_prev(mm, addr, &prev); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma)) && -+ (!prev || addr >= vm_end_gap(prev))) - goto found_addr; - } - ---- a/arch/powerpc/mm/hugetlbpage-radix.c -+++ b/arch/powerpc/mm/hugetlbpage-radix.c -@@ -65,7 +65,7 @@ radix__hugetlb_get_unmapped_area(struct - addr = ALIGN(addr, huge_page_size(h)); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - /* ---- a/arch/powerpc/mm/mmap.c -+++ b/arch/powerpc/mm/mmap.c -@@ -107,7 +107,7 @@ radix__arch_get_unmapped_area(struct fil - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -143,7 +143,7 @@ radix__arch_get_unmapped_area_topdown(st - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/powerpc/mm/slice.c -+++ b/arch/powerpc/mm/slice.c -@@ -105,7 +105,7 @@ static int slice_area_is_free(struct mm_ - if ((mm->task_size - len) < addr) - return 0; - vma = find_vma(mm, addr); -- return (!vma || (addr + len) <= vma->vm_start); -+ return (!vma || (addr + len) <= vm_start_gap(vma)); - } - - static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice) ---- a/arch/s390/mm/mmap.c -+++ b/arch/s390/mm/mmap.c -@@ -100,7 +100,7 @@ arch_get_unmapped_area(struct file *filp - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -138,7 +138,7 @@ arch_get_unmapped_area_topdown(struct fi - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/sh/mm/mmap.c -+++ b/arch/sh/mm/mmap.c -@@ -64,7 +64,7 @@ unsigned long arch_get_unmapped_area(str - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -114,7 +114,7 @@ arch_get_unmapped_area_topdown(struct fi - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/sparc/kernel/sys_sparc_64.c -+++ b/arch/sparc/kernel/sys_sparc_64.c -@@ -120,7 +120,7 @@ unsigned long arch_get_unmapped_area(str - - vma = find_vma(mm, addr); - if (task_size - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -183,7 +183,7 @@ arch_get_unmapped_area_topdown(struct fi - - vma = find_vma(mm, addr); - if (task_size - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/sparc/mm/hugetlbpage.c -+++ b/arch/sparc/mm/hugetlbpage.c -@@ -120,7 +120,7 @@ hugetlb_get_unmapped_area(struct file *f - addr = ALIGN(addr, huge_page_size(h)); - vma = find_vma(mm, addr); - if (task_size - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - if (mm->get_unmapped_area == arch_get_unmapped_area) ---- a/arch/tile/mm/hugetlbpage.c -+++ b/arch/tile/mm/hugetlbpage.c -@@ -233,7 +233,7 @@ unsigned long hugetlb_get_unmapped_area( - addr = ALIGN(addr, huge_page_size(h)); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - if (current->mm->get_unmapped_area == arch_get_unmapped_area) ---- a/arch/x86/kernel/sys_x86_64.c -+++ b/arch/x86/kernel/sys_x86_64.c -@@ -141,7 +141,7 @@ arch_get_unmapped_area(struct file *filp - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (end - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - -@@ -184,7 +184,7 @@ arch_get_unmapped_area_topdown(struct fi - addr = PAGE_ALIGN(addr); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/arch/x86/mm/hugetlbpage.c -+++ b/arch/x86/mm/hugetlbpage.c -@@ -145,7 +145,7 @@ hugetlb_get_unmapped_area(struct file *f - addr = ALIGN(addr, huge_page_size(h)); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - if (mm->get_unmapped_area == arch_get_unmapped_area) ---- a/arch/xtensa/kernel/syscall.c -+++ b/arch/xtensa/kernel/syscall.c -@@ -88,7 +88,7 @@ unsigned long arch_get_unmapped_area(str - /* At this point: (!vmm || addr < vmm->vm_end). */ - if (TASK_SIZE - len < addr) - return -ENOMEM; -- if (!vmm || addr + len <= vmm->vm_start) -+ if (!vmm || addr + len <= vm_start_gap(vmm)) - return addr; - addr = vmm->vm_end; - if (flags & MAP_SHARED) ---- a/fs/hugetlbfs/inode.c -+++ b/fs/hugetlbfs/inode.c -@@ -200,7 +200,7 @@ hugetlb_get_unmapped_area(struct file *f - addr = ALIGN(addr, huge_page_size(h)); - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } - ---- a/fs/proc/task_mmu.c -+++ b/fs/proc/task_mmu.c -@@ -303,11 +303,7 @@ show_map_vma(struct seq_file *m, struct - - /* We don't show the stack guard page in /proc/maps */ - start = vma->vm_start; -- if (stack_guard_page_start(vma, start)) -- start += PAGE_SIZE; - end = vma->vm_end; -- if (stack_guard_page_end(vma, end)) -- end -= PAGE_SIZE; - - seq_setwidth(m, 25 + sizeof(void *) * 6 - 1); - seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ", ---- a/include/linux/mm.h -+++ b/include/linux/mm.h -@@ -1403,12 +1403,6 @@ int clear_page_dirty_for_io(struct page - - int get_cmdline(struct task_struct *task, char *buffer, int buflen); - --/* Is the vma a continuation of the stack vma above it? */ --static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr) --{ -- return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN); --} -- - static inline bool vma_is_anonymous(struct vm_area_struct *vma) - { - return !vma->vm_ops; -@@ -1424,28 +1418,6 @@ bool vma_is_shmem(struct vm_area_struct - static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; } - #endif - --static inline int stack_guard_page_start(struct vm_area_struct *vma, -- unsigned long addr) --{ -- return (vma->vm_flags & VM_GROWSDOWN) && -- (vma->vm_start == addr) && -- !vma_growsdown(vma->vm_prev, addr); --} -- --/* Is the vma a continuation of the stack vma below it? */ --static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr) --{ -- return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP); --} -- --static inline int stack_guard_page_end(struct vm_area_struct *vma, -- unsigned long addr) --{ -- return (vma->vm_flags & VM_GROWSUP) && -- (vma->vm_end == addr) && -- !vma_growsup(vma->vm_next, addr); --} -- - int vma_is_stack_for_current(struct vm_area_struct *vma); - - extern unsigned long move_page_tables(struct vm_area_struct *vma, -@@ -2232,6 +2204,7 @@ void page_cache_async_readahead(struct a - pgoff_t offset, - unsigned long size); - -+extern unsigned long stack_guard_gap; - /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */ - extern int expand_stack(struct vm_area_struct *vma, unsigned long address); - -@@ -2260,6 +2233,30 @@ static inline struct vm_area_struct * fi - return vma; - } - -+static inline unsigned long vm_start_gap(struct vm_area_struct *vma) -+{ -+ unsigned long vm_start = vma->vm_start; -+ -+ if (vma->vm_flags & VM_GROWSDOWN) { -+ vm_start -= stack_guard_gap; -+ if (vm_start > vma->vm_start) -+ vm_start = 0; -+ } -+ return vm_start; -+} -+ -+static inline unsigned long vm_end_gap(struct vm_area_struct *vma) -+{ -+ unsigned long vm_end = vma->vm_end; -+ -+ if (vma->vm_flags & VM_GROWSUP) { -+ vm_end += stack_guard_gap; -+ if (vm_end < vma->vm_end) -+ vm_end = -PAGE_SIZE; -+ } -+ return vm_end; -+} -+ - static inline unsigned long vma_pages(struct vm_area_struct *vma) - { - return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; ---- a/mm/gup.c -+++ b/mm/gup.c -@@ -387,11 +387,6 @@ static int faultin_page(struct task_stru - /* mlock all present pages, but do not fault in new pages */ - if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK) - return -ENOENT; -- /* For mm_populate(), just skip the stack guard page. */ -- if ((*flags & FOLL_POPULATE) && -- (stack_guard_page_start(vma, address) || -- stack_guard_page_end(vma, address + PAGE_SIZE))) -- return -ENOENT; - if (*flags & FOLL_WRITE) - fault_flags |= FAULT_FLAG_WRITE; - if (*flags & FOLL_REMOTE) ---- a/mm/memory.c -+++ b/mm/memory.c -@@ -2855,40 +2855,6 @@ out_release: - } - - /* -- * This is like a special single-page "expand_{down|up}wards()", -- * except we must first make sure that 'address{-|+}PAGE_SIZE' -- * doesn't hit another vma. -- */ --static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) --{ -- address &= PAGE_MASK; -- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { -- struct vm_area_struct *prev = vma->vm_prev; -- -- /* -- * Is there a mapping abutting this one below? -- * -- * That's only ok if it's the same stack mapping -- * that has gotten split.. -- */ -- if (prev && prev->vm_end == address) -- return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; -- -- return expand_downwards(vma, address - PAGE_SIZE); -- } -- if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { -- struct vm_area_struct *next = vma->vm_next; -- -- /* As VM_GROWSDOWN but s/below/above/ */ -- if (next && next->vm_start == address + PAGE_SIZE) -- return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; -- -- return expand_upwards(vma, address + PAGE_SIZE); -- } -- return 0; --} -- --/* - * We enter with non-exclusive mmap_sem (to exclude vma changes, - * but allow concurrent faults), and pte mapped but not yet locked. - * We return with mmap_sem still held, but pte unmapped and unlocked. -@@ -2904,10 +2870,6 @@ static int do_anonymous_page(struct vm_f - if (vma->vm_flags & VM_SHARED) - return VM_FAULT_SIGBUS; - -- /* Check if we need to add a guard page to the stack */ -- if (check_stack_guard_page(vma, vmf->address) < 0) -- return VM_FAULT_SIGSEGV; -- - /* - * Use pte_alloc() instead of pte_alloc_map(). We can't run - * pte_offset_map() on pmds where a huge pmd might be created ---- a/mm/mmap.c -+++ b/mm/mmap.c -@@ -183,6 +183,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) - unsigned long retval; - unsigned long newbrk, oldbrk; - struct mm_struct *mm = current->mm; -+ struct vm_area_struct *next; - unsigned long min_brk; - bool populate; - LIST_HEAD(uf); -@@ -229,7 +230,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk) - } - - /* Check against existing mmap mappings. */ -- if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) -+ next = find_vma(mm, oldbrk); -+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) - goto out; - - /* Ok, looks good - let it rip. */ -@@ -253,10 +255,22 @@ out: - - static long vma_compute_subtree_gap(struct vm_area_struct *vma) - { -- unsigned long max, subtree_gap; -- max = vma->vm_start; -- if (vma->vm_prev) -- max -= vma->vm_prev->vm_end; -+ unsigned long max, prev_end, subtree_gap; -+ -+ /* -+ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we -+ * allow two stack_guard_gaps between them here, and when choosing -+ * an unmapped area; whereas when expanding we only require one. -+ * That's a little inconsistent, but keeps the code here simpler. -+ */ -+ max = vm_start_gap(vma); -+ if (vma->vm_prev) { -+ prev_end = vm_end_gap(vma->vm_prev); -+ if (max > prev_end) -+ max -= prev_end; -+ else -+ max = 0; -+ } - if (vma->vm_rb.rb_left) { - subtree_gap = rb_entry(vma->vm_rb.rb_left, - struct vm_area_struct, vm_rb)->rb_subtree_gap; -@@ -352,7 +366,7 @@ static void validate_mm(struct mm_struct - anon_vma_unlock_read(anon_vma); - } - -- highest_address = vma->vm_end; -+ highest_address = vm_end_gap(vma); - vma = vma->vm_next; - i++; - } -@@ -541,7 +555,7 @@ void __vma_link_rb(struct mm_struct *mm, - if (vma->vm_next) - vma_gap_update(vma->vm_next); - else -- mm->highest_vm_end = vma->vm_end; -+ mm->highest_vm_end = vm_end_gap(vma); - - /* - * vma->vm_prev wasn't known when we followed the rbtree to find the -@@ -856,7 +870,7 @@ again: - vma_gap_update(vma); - if (end_changed) { - if (!next) -- mm->highest_vm_end = end; -+ mm->highest_vm_end = vm_end_gap(vma); - else if (!adjust_next) - vma_gap_update(next); - } -@@ -941,7 +955,7 @@ again: - * mm->highest_vm_end doesn't need any update - * in remove_next == 1 case. - */ -- VM_WARN_ON(mm->highest_vm_end != end); -+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); - } - } - if (insert && file) -@@ -1787,7 +1801,7 @@ unsigned long unmapped_area(struct vm_un - - while (true) { - /* Visit left subtree if it looks promising */ -- gap_end = vma->vm_start; -+ gap_end = vm_start_gap(vma); - if (gap_end >= low_limit && vma->vm_rb.rb_left) { - struct vm_area_struct *left = - rb_entry(vma->vm_rb.rb_left, -@@ -1798,7 +1812,7 @@ unsigned long unmapped_area(struct vm_un - } - } - -- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; -+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; - check_current: - /* Check if current node has a suitable gap */ - if (gap_start > high_limit) -@@ -1825,8 +1839,8 @@ check_current: - vma = rb_entry(rb_parent(prev), - struct vm_area_struct, vm_rb); - if (prev == vma->vm_rb.rb_left) { -- gap_start = vma->vm_prev->vm_end; -- gap_end = vma->vm_start; -+ gap_start = vm_end_gap(vma->vm_prev); -+ gap_end = vm_start_gap(vma); - goto check_current; - } - } -@@ -1890,7 +1904,7 @@ unsigned long unmapped_area_topdown(stru - - while (true) { - /* Visit right subtree if it looks promising */ -- gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; -+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; - if (gap_start <= high_limit && vma->vm_rb.rb_right) { - struct vm_area_struct *right = - rb_entry(vma->vm_rb.rb_right, -@@ -1903,7 +1917,7 @@ unsigned long unmapped_area_topdown(stru - - check_current: - /* Check if current node has a suitable gap */ -- gap_end = vma->vm_start; -+ gap_end = vm_start_gap(vma); - if (gap_end < low_limit) - return -ENOMEM; - if (gap_start <= high_limit && gap_end - gap_start >= length) -@@ -1929,7 +1943,7 @@ check_current: - struct vm_area_struct, vm_rb); - if (prev == vma->vm_rb.rb_right) { - gap_start = vma->vm_prev ? -- vma->vm_prev->vm_end : 0; -+ vm_end_gap(vma->vm_prev) : 0; - goto check_current; - } - } -@@ -1967,7 +1981,7 @@ arch_get_unmapped_area(struct file *filp - unsigned long len, unsigned long pgoff, unsigned long flags) - { - struct mm_struct *mm = current->mm; -- struct vm_area_struct *vma; -+ struct vm_area_struct *vma, *prev; - struct vm_unmapped_area_info info; - - if (len > TASK_SIZE - mmap_min_addr) -@@ -1978,9 +1992,10 @@ arch_get_unmapped_area(struct file *filp - - if (addr) { - addr = PAGE_ALIGN(addr); -- vma = find_vma(mm, addr); -+ vma = find_vma_prev(mm, addr, &prev); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma)) && -+ (!prev || addr >= vm_end_gap(prev))) - return addr; - } - -@@ -2003,7 +2018,7 @@ arch_get_unmapped_area_topdown(struct fi - const unsigned long len, const unsigned long pgoff, - const unsigned long flags) - { -- struct vm_area_struct *vma; -+ struct vm_area_struct *vma, *prev; - struct mm_struct *mm = current->mm; - unsigned long addr = addr0; - struct vm_unmapped_area_info info; -@@ -2018,9 +2033,10 @@ arch_get_unmapped_area_topdown(struct fi - /* requesting a specific address */ - if (addr) { - addr = PAGE_ALIGN(addr); -- vma = find_vma(mm, addr); -+ vma = find_vma_prev(mm, addr, &prev); - if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && -- (!vma || addr + len <= vma->vm_start)) -+ (!vma || addr + len <= vm_start_gap(vma)) && -+ (!prev || addr >= vm_end_gap(prev))) - return addr; - } - -@@ -2155,21 +2171,19 @@ find_vma_prev(struct mm_struct *mm, unsi - * update accounting. This is shared with both the - * grow-up and grow-down cases. - */ --static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) -+static int acct_stack_growth(struct vm_area_struct *vma, -+ unsigned long size, unsigned long grow) - { - struct mm_struct *mm = vma->vm_mm; - struct rlimit *rlim = current->signal->rlim; -- unsigned long new_start, actual_size; -+ unsigned long new_start; - - /* address space limit tests */ - if (!may_expand_vm(mm, vma->vm_flags, grow)) - return -ENOMEM; - - /* Stack limit test */ -- actual_size = size; -- if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN))) -- actual_size -= PAGE_SIZE; -- if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur)) -+ if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur)) - return -ENOMEM; - - /* mlock limit tests */ -@@ -2207,17 +2221,30 @@ static int acct_stack_growth(struct vm_a - int expand_upwards(struct vm_area_struct *vma, unsigned long address) - { - struct mm_struct *mm = vma->vm_mm; -+ struct vm_area_struct *next; -+ unsigned long gap_addr; - int error = 0; - - if (!(vma->vm_flags & VM_GROWSUP)) - return -EFAULT; - - /* Guard against wrapping around to address 0. */ -- if (address < PAGE_ALIGN(address+4)) -- address = PAGE_ALIGN(address+4); -- else -+ address &= PAGE_MASK; -+ address += PAGE_SIZE; -+ if (!address) - return -ENOMEM; - -+ /* Enforce stack_guard_gap */ -+ gap_addr = address + stack_guard_gap; -+ if (gap_addr < address) -+ return -ENOMEM; -+ next = vma->vm_next; -+ if (next && next->vm_start < gap_addr) { -+ if (!(next->vm_flags & VM_GROWSUP)) -+ return -ENOMEM; -+ /* Check that both stack segments have the same anon_vma? */ -+ } -+ - /* We must make sure the anon_vma is allocated. */ - if (unlikely(anon_vma_prepare(vma))) - return -ENOMEM; -@@ -2261,7 +2288,7 @@ int expand_upwards(struct vm_area_struct - if (vma->vm_next) - vma_gap_update(vma->vm_next); - else -- mm->highest_vm_end = address; -+ mm->highest_vm_end = vm_end_gap(vma); - spin_unlock(&mm->page_table_lock); - - perf_event_mmap(vma); -@@ -2282,6 +2309,8 @@ int expand_downwards(struct vm_area_stru - unsigned long address) - { - struct mm_struct *mm = vma->vm_mm; -+ struct vm_area_struct *prev; -+ unsigned long gap_addr; - int error; - - address &= PAGE_MASK; -@@ -2289,6 +2318,17 @@ int expand_downwards(struct vm_area_stru - if (error) - return error; - -+ /* Enforce stack_guard_gap */ -+ gap_addr = address - stack_guard_gap; -+ if (gap_addr > address) -+ return -ENOMEM; -+ prev = vma->vm_prev; -+ if (prev && prev->vm_end > gap_addr) { -+ if (!(prev->vm_flags & VM_GROWSDOWN)) -+ return -ENOMEM; -+ /* Check that both stack segments have the same anon_vma? */ -+ } -+ - /* We must make sure the anon_vma is allocated. */ - if (unlikely(anon_vma_prepare(vma))) - return -ENOMEM; -@@ -2343,28 +2383,25 @@ int expand_downwards(struct vm_area_stru - return error; - } - --/* -- * Note how expand_stack() refuses to expand the stack all the way to -- * abut the next virtual mapping, *unless* that mapping itself is also -- * a stack mapping. We want to leave room for a guard page, after all -- * (the guard page itself is not added here, that is done by the -- * actual page faulting logic) -- * -- * This matches the behavior of the guard page logic (see mm/memory.c: -- * check_stack_guard_page()), which only allows the guard page to be -- * removed under these circumstances. -- */ -+/* enforced gap between the expanding stack and other mappings. */ -+unsigned long stack_guard_gap = 256UL<