From cef8e147af26fd202bc668a26d6ffdc0f8685664 Mon Sep 17 00:00:00 2001 From: Andreas Radke Date: Tue, 6 Dec 2016 12:09:59 +0000 Subject: [PATCH] CVE-2016-8655 --- PKGBUILD | 12 +++- fix_race_condition_in_packet_set_ring.diff | 84 ++++++++++++++++++++++ 2 files changed, 93 insertions(+), 3 deletions(-) create mode 100644 fix_race_condition_in_packet_set_ring.diff diff --git a/PKGBUILD b/PKGBUILD index fc99044..ef2a47c 100644 --- a/PKGBUILD +++ b/PKGBUILD @@ -6,9 +6,9 @@ pkgbase=linux # Build stock -ARCH kernel #pkgbase=linux-custom # Build kernel with a different name _srcname=linux-4.8 pkgver=4.8.12 -pkgrel=1 +pkgrel=2 arch=('i686' 'x86_64') -url="http://www.kernel.org/" +url="https://www.kernel.org/" license=('GPL2') makedepends=('xmlto' 'docbook-xsl' 'kmod' 'inetutils' 'bc' 'libelf') options=('!strip') @@ -23,6 +23,7 @@ source=("https://www.kernel.org/pub/linux/kernel/v4.x/${_srcname}.tar.xz" # standard config files for mkinitcpio ramdisk 'linux.preset' 'change-default-console-loglevel.patch' + fix_race_condition_in_packet_set_ring.diff ) sha256sums=('3e9150065f193d3d94bcf46a1fe9f033c7ef7122ab71d75a7fb5a2f0c9a7e11a' @@ -33,7 +34,8 @@ sha256sums=('3e9150065f193d3d94bcf46a1fe9f033c7ef7122ab71d75a7fb5a2f0c9a7e11a' '41b9a64542befd2fea170776e8ec22a7d158dd3273633afc9b91662c448cd90a' '834bd254b56ab71d73f59b3221f056c72f559553c04718e350ab2a3e2991afe0' 'ad6344badc91ad0630caacde83f7f9b97276f80d26a20619a87952be65492c65' - '1256b241cd477b265a3c2d64bdc19ffe3c9bbcee82ea3994c590c2c76e767d99') + '1256b241cd477b265a3c2d64bdc19ffe3c9bbcee82ea3994c590c2c76e767d99' + 'ad1ee95f906f88d31fcdb9273cd08e02e8eda177449f0c98dc1bff8cbf1483c2') validpgpkeys=( 'ABAF11C65A2970B130ABE3C479BE3E4300411886' # Linus Torvalds '647F28654894E3BD457199BE38DBBDC86092693E' # Greg Kroah-Hartman @@ -47,6 +49,10 @@ prepare() { # add upstream patch patch -p1 -i "${srcdir}/patch-${pkgver}" + # fix a race condition that allows to gain root + # https://marc.info/?l=linux-netdev&m=148054660230570&w=2 + patch -p1 -i "${srcdir}/fix_race_condition_in_packet_set_ring.diff" + # add latest fixes from stable queue, if needed # http://git.kernel.org/?p=linux/kernel/git/stable/stable-queue.git diff --git a/fix_race_condition_in_packet_set_ring.diff b/fix_race_condition_in_packet_set_ring.diff new file mode 100644 index 0000000..12048f6 --- /dev/null +++ b/fix_race_condition_in_packet_set_ring.diff @@ -0,0 +1,84 @@ +From: Philip Pettersson + +When packet_set_ring creates a ring buffer it will initialize a +struct timer_list if the packet version is TPACKET_V3. This value +can then be raced by a different thread calling setsockopt to +set the version to TPACKET_V1 before packet_set_ring has finished. + +This leads to a use-after-free on a function pointer in the +struct timer_list when the socket is closed as the previously +initialized timer will not be deleted. + +The bug is fixed by taking lock_sock(sk) in packet_setsockopt when +changing the packet version while also taking the lock at the start +of packet_set_ring. + +Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.") +Signed-off-by: Philip Pettersson +Signed-off-by: Eric Dumazet +--- + net/packet/af_packet.c | 18 ++++++++++++------ + 1 file changed, 12 insertions(+), 6 deletions(-) + +diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c +index d2238b204691b8e4f2e3acb9bc167b553ba32d50..dd2332390c45bbff7c3fc5d259453f2e1ca352bf 100644 +--- a/net/packet/af_packet.c ++++ b/net/packet/af_packet.c +@@ -3648,19 +3648,25 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv + + if (optlen != sizeof(val)) + return -EINVAL; +- if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) +- return -EBUSY; + if (copy_from_user(&val, optval, sizeof(val))) + return -EFAULT; + switch (val) { + case TPACKET_V1: + case TPACKET_V2: + case TPACKET_V3: +- po->tp_version = val; +- return 0; ++ break; + default: + return -EINVAL; + } ++ lock_sock(sk); ++ if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) { ++ ret = -EBUSY; ++ } else { ++ po->tp_version = val; ++ ret = 0; ++ } ++ release_sock(sk); ++ return ret; + } + case PACKET_RESERVE: + { +@@ -4164,6 +4170,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, + /* Added to avoid minimal code churn */ + struct tpacket_req *req = &req_u->req; + ++ lock_sock(sk); + /* Opening a Tx-ring is NOT supported in TPACKET_V3 */ + if (!closing && tx_ring && (po->tp_version > TPACKET_V2)) { + net_warn_ratelimited("Tx-ring is not supported.\n"); +@@ -4245,7 +4252,6 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, + goto out; + } + +- lock_sock(sk); + + /* Detach socket from network */ + spin_lock(&po->bind_lock); +@@ -4294,11 +4300,11 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, + if (!tx_ring) + prb_shutdown_retire_blk_timer(po, rb_queue); + } +- release_sock(sk); + + if (pg_vec) + free_pg_vec(pg_vec, order, req->tp_block_nr); + out: ++ release_sock(sk); + return err; + }