From e5dfc5da18f3734979f44c47f1442484b40feb24 Mon Sep 17 00:00:00 2001 From: Sona Sarmadi Date: Fri, 29 Sep 2017 12:28:01 +0200 Subject: linux-cavium: CVE-2017-5669 Shmat allows mmap null page protection bypass Reference: https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-5669 Signed-off-by: Sona Sarmadi Signed-off-by: Adrian Dudau --- .../linux/linux-cavium/CVE-2017-5669.patch | 81 ++++++++++++++++++++++ recipes-kernel/linux/linux-cavium_4.9.inc | 1 + 2 files changed, 82 insertions(+) create mode 100644 recipes-kernel/linux/linux-cavium/CVE-2017-5669.patch diff --git a/recipes-kernel/linux/linux-cavium/CVE-2017-5669.patch b/recipes-kernel/linux/linux-cavium/CVE-2017-5669.patch new file mode 100644 index 0000000..7dcd09a --- /dev/null +++ b/recipes-kernel/linux/linux-cavium/CVE-2017-5669.patch @@ -0,0 +1,81 @@ +From 270e84a1e6effd6c0c6e9b13b196b5fdaa392954 Mon Sep 17 00:00:00 2001 +From: Davidlohr Bueso +Date: Mon, 27 Feb 2017 14:28:24 -0800 +Subject: [PATCH] ipc/shm: Fix shmat mmap nil-page protection + +commit 95e91b831f87ac8e1f8ed50c14d709089b4e01b8 upstream. + +The issue is described here, with a nice testcase: + + https://bugzilla.kernel.org/show_bug.cgi?id=192931 + +The problem is that shmat() calls do_mmap_pgoff() with MAP_FIXED, and +the address rounded down to 0. For the regular mmap case, the +protection mentioned above is that the kernel gets to generate the +address -- arch_get_unmapped_area() will always check for MAP_FIXED and +return that address. So by the time we do security_mmap_addr(0) things +get funky for shmat(). + +The testcase itself shows that while a regular user crashes, root will +not have a problem attaching a nil-page. There are two possible fixes +to this. The first, and which this patch does, is to simply allow root +to crash as well -- this is also regular mmap behavior, ie when hacking +up the testcase and adding mmap(... |MAP_FIXED). While this approach +is the safer option, the second alternative is to ignore SHM_RND if the +rounded address is 0, thus only having MAP_SHARED flags. This makes the +behavior of shmat() identical to the mmap() case. The downside of this +is obviously user visible, but does make sense in that it maintains +semantics after the round-down wrt 0 address and mmap. + +Passes shm related ltp tests. + +CVE: CVE-2017-5669 +Upstream-Status: Backport [from kernel.org longterm 4.9.52] + +Link: http://lkml.kernel.org/r/1486050195-18629-1-git-send-email-dave@stgolabs.net +Signed-off-by: Davidlohr Bueso +Reported-by: Gareth Evans +Cc: Manfred Spraul +Cc: Michael Kerrisk +Signed-off-by: Andrew Morton +Signed-off-by: Linus Torvalds +Signed-off-by: Greg Kroah-Hartman +Signed-off-by: Sona Sarmadi +--- + ipc/shm.c | 13 +++++++++---- + 1 file changed, 9 insertions(+), 4 deletions(-) + +diff --git a/ipc/shm.c b/ipc/shm.c +index dbac886..e2072ae 100644 +--- a/ipc/shm.c ++++ b/ipc/shm.c +@@ -1085,8 +1085,8 @@ static int shmctl_nolock(struct ipc_namespace *ns, int shmid, + * "raddr" thing points to kernel space, and there has to be a wrapper around + * this. + */ +-long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, +- unsigned long shmlba) ++long do_shmat(int shmid, char __user *shmaddr, int shmflg, ++ ulong *raddr, unsigned long shmlba) + { + struct shmid_kernel *shp; + unsigned long addr; +@@ -1107,8 +1107,13 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, + goto out; + else if ((addr = (ulong)shmaddr)) { + if (addr & (shmlba - 1)) { +- if (shmflg & SHM_RND) +- addr &= ~(shmlba - 1); /* round down */ ++ /* ++ * Round down to the nearest multiple of shmlba. ++ * For sane do_mmap_pgoff() parameters, avoid ++ * round downs that trigger nil-page and MAP_FIXED. ++ */ ++ if ((shmflg & SHM_RND) && addr >= shmlba) ++ addr &= ~(shmlba - 1); + else + #ifndef __ARCH_FORCE_SHMLBA + if (addr & ~PAGE_MASK) +-- +1.9.1 + diff --git a/recipes-kernel/linux/linux-cavium_4.9.inc b/recipes-kernel/linux/linux-cavium_4.9.inc index 8ff28fd..e35c12f 100644 --- a/recipes-kernel/linux/linux-cavium_4.9.inc +++ b/recipes-kernel/linux/linux-cavium_4.9.inc @@ -19,6 +19,7 @@ SRC_URI = "git://git@git.enea.com/linux/linux-cavium.git;protocol=ssh;name=machi file://CVE-2016-10208.patch \ file://CVE-2017-5551.patch \ file://CVE-2017-5577.patch \ + file://CVE-2017-5669.patch \ file://CVE-2017-7487.patch \ file://CVE-2017-7618.patch \ file://CVE-2017-7645.patch \ -- cgit v1.2.3-54-g00ecf