Red Hat Bugzilla – Bug 1094363
CVE-2014-0203 kernel: fs: slab corruption due to the invalid last component type during do_filp_open()
Last modified: 2015-07-31 03:20:00 EDT
It was found that proc_ns_follow_link() doesn't return LAST_BIND (unlike proc_pid_follow_link()) which leads to the slab corruption caused by (excessive) putname() in do_filp_open(). The slab corruption later manifests itself in the form of BUG() in cache_alloc_refill() when performing "$ echo > /proc/$$/ns/pid" -- kernel BUG at mm/slab.c:3069! invalid opcode: 0000 [#1] SMP last sysfs file: /sys/devices/system/node/node0/meminfo CPU 1 Modules linked in: Pid: 2249, comm: bash Not tainted 2.6.32-431.5.1.el6.x86_64 #1 RIP: 0010:[<ffffffff8116ed14>] [<ffffffff8116ed14>] cache_alloc_refill+0x1e4/0x240 RSP: 0018:ffff88007b69fe38 EFLAGS: 00010082 RAX: 000000000000000c RBX: ffff88007ec30f00 RCX: 00000000ffffffff RDX: 000000000000000c RSI: 0000000000000000 RDI: ffff88007fa96580 RBP: ffff88007b69fe98 R08: 0000000000000000 R09: 000000000000002a R10: 0000000000000076 R11: 0000000000000000 R12: ffff88007fa96580 R13: ffff88007fae8c40 R14: 000000000000000c R15: ffff88007d9386c0 FS: 00007f6f8819b700(0000) GS:ffff88000c420000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006d3d88 CR3: 00000000374d1000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process bash (pid: 2249, threadinfo ffff88007b69e000, task ffff8800379a5540) Stack: ffff88007b69fe58 00000000811a1edf ffff88007fae8c80 000412d07bdf1500 ffff88007fae8c60 ffff88007fae8c50 ffff88007b69feb8 0000000001440530 00000000000000d0 ffff88007ec30f00 00000000000000d0 0000000000000246 Call Trace: [<ffffffff8116fdcf>] kmem_cache_alloc+0x15f/0x190 [<ffffffff81196ff7>] getname+0x47/0x240 [<ffffffff81185ce2>] do_sys_open+0x32/0x140 [<ffffffff81185e30>] sys_open+0x20/0x30 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b Code: 89 ff e8 70 57 12 00 eb 99 66 0f 1f 44 00 00 41 c7 45 60 01 00 00 00 4d 8b 7d 20 4c 39 7d c0 0f 85 f2 fe ff ff eb 84 0f 0b eb fe <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 eb f4 8b 55 ac 8b 75 bc 31 RIP [<ffffffff8116ed14>] cache_alloc_refill+0x1e4/0x240 RSP <ffff88007b69fe38> An unprivileged local user could use this flaw to crash the system. Upstream fix: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=86acdca1b63e6890540fa19495cfc708beff3d8b Acknowledgements: Red Hat would like to thank Vladimir Davydov of Parallels for reporting this issue.
Statement: This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 7 and Red Hat Enterprise MRG 2.
This issue has been addressed in following products: Red Hat Enterprise Linux 6 Via RHSA-2014:0771 https://rhn.redhat.com/errata/RHSA-2014-0771.html