From patchwork Tue Dec 6 16:32:05 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [hardy, lucid, lucid/fsl-imx51, maverick, maverick/ti-omap4, natty, natty/ti-omap4, CVE, 1/1] KEYS: Fix a NULL pointer deref in the user-defined key type Date: Tue, 06 Dec 2011 06:32:05 -0000 From: Andy Whitcroft X-Patchwork-Id: 129733 Message-Id: <1323189125-20157-2-git-send-email-apw@canonical.com> To: kernel-team@lists.ubuntu.com Cc: Andy Whitcroft From: David Howells Fix a NULL pointer deref in the user-defined key type whereby updating a negative key into a fully instantiated key will cause an oops to occur when the code attempts to free the non-existent old payload. This results in an oops that looks something like the following: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [] __call_rcu+0x11/0x13e PGD 3391d067 PUD 3894a067 PMD 0 Oops: 0002 [#1] SMP CPU 1 Pid: 4354, comm: keyctl Not tainted 3.1.0-fsdevel+ #1140 /DG965RY RIP: 0010:[] [] __call_rcu+0x11/0x13e RSP: 0018:ffff88003d591df8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000006e RDX: ffffffff8161d0c0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff88003d591e18 R08: 0000000000000000 R09: ffffffff8152fa6c R10: 0000000000000000 R11: 0000000000000300 R12: ffff88003b8f9538 R13: ffffffff8161d0c0 R14: ffff88003b8f9d50 R15: ffff88003c69f908 FS: 00007f97eb18c720(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000003d47a000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process keyctl (pid: 4354, threadinfo ffff88003d590000, task ffff88003c78a040) Stack: ffff88003e0ffde0 ffff88003b8f9538 0000000000000001 ffff88003b8f9d50 ffff88003d591e28 ffffffff810860f0 ffff88003d591e68 ffffffff8117bfea ffff88003d591e68 ffffffff00000000 ffff88003e0ffde1 ffff88003e0ffde0 Call Trace: [] call_rcu_sched+0x10/0x12 [] user_update+0x8d/0xa2 [] key_create_or_update+0x236/0x270 [] sys_add_key+0x123/0x17e [] system_call_fastpath+0x16/0x1b Signed-off-by: David Howells Acked-by: Jeff Layton Acked-by: Neil Horman Acked-by: Steve Dickson Acked-by: James Morris Cc: stable@kernel.org Signed-off-by: Linus Torvalds (backported from commit 9f35a33b8d06263a165efe3541d9aa0cdbd70b3b) CVE-2011-4110 BugLink: http://bugs.launchpad.net/bugs/894369 Signed-off-by: Andy Whitcroft Acked-by: Seth Forshee --- security/keys/user_defined.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c index 7c687d5..97edf29 100644 --- a/security/keys/user_defined.c +++ b/security/keys/user_defined.c @@ -119,7 +119,8 @@ int user_update(struct key *key, const void *data, size_t datalen) key->expiry = 0; } - call_rcu(&zap->rcu, user_update_rcu_disposal); + if (zap) + call_rcu(&zap->rcu, user_update_rcu_disposal); error: return ret;