CVE-2023-53564

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: fix defrag path triggering jbd2 ASSERT

code path:

ocfs2_ioctl_move_extents ocfs2_move_extents ocfs2_defrag_extent __ocfs2_move_extent + ocfs2_journal_access_di + ocfs2_split_extent //sub-paths call jbd2_journal_restart + ocfs2_journal_dirty //crash by jbs2 ASSERT

crash stacks:

PID: 11297 TASK: ffff974a676dcd00 CPU: 67 COMMAND: defragfs.ocfs2 #0 [ffffb25d8dad3900] machine_kexec at ffffffff8386fe01 #1 [ffffb25d8dad3958] __crash_kexec at ffffffff8395959d #2 [ffffb25d8dad3a20] crash_kexec at ffffffff8395a45d #3 [ffffb25d8dad3a38] oops_end at ffffffff83836d3f #4 [ffffb25d8dad3a58] do_trap at ffffffff83833205 #5 [ffffb25d8dad3aa0] do_invalid_op at ffffffff83833aa6 #6 [ffffb25d8dad3ac0] invalid_op at ffffffff84200d18 [exception RIP: jbd2_journal_dirty_metadata+0x2ba] RIP: ffffffffc09ca54a RSP: ffffb25d8dad3b70 RFLAGS: 00010207 RAX: 0000000000000000 RBX: ffff9706eedc5248 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffff97337029ea28 RDI: ffff9706eedc5250 RBP: ffff9703c3520200 R8: 000000000f46b0b2 R9: 0000000000000000 R10: 0000000000000001 R11: 00000001000000fe R12: ffff97337029ea28 R13: 0000000000000000 R14: ffff9703de59bf60 R15: ffff9706eedc5250 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #7 [ffffb25d8dad3ba8] ocfs2_journal_dirty at ffffffffc137fb95 [ocfs2] #8 [ffffb25d8dad3be8] __ocfs2_move_extent at ffffffffc139a950 [ocfs2] #9 [ffffb25d8dad3c80] ocfs2_defrag_extent at ffffffffc139b2d2 [ocfs2]

Analysis

This bug has the same root cause of commit 7f27ec978b0e (ocfs2: call ocfs2_journal_access_di() before ocfs2_journal_dirty() in ocfs2_write_end_nolock()). For this bug, jbd2_journal_restart() is called by ocfs2_split_extent() during defragmenting.

How to fix

For ocfs2_split_extent() can handle journal operations totally by itself. Caller doesnt need to call journal access/dirty pair, and caller only needs to call journal start/stop pair. The fix method is to remove journal access/dirty from __ocfs2_move_extent().

The discussion for this patch: https://oss.oracle.com/pipermail/ocfs2-devel/2023-February/000647.html

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/2c559b3ba8e0b9e3c4bb08159a28ccadc698410f
• https://git.kernel.org/stable/c/33665d1042666f2e5c736a3df1f453e31f030663
• https://git.kernel.org/stable/c/590507ebabd33cd93324c04f9a5538309a5ba934
• https://git.kernel.org/stable/c/5f43d34a51ed30e6a60f7e59d224a63014fe2cd5
• https://git.kernel.org/stable/c/60eed1e3d45045623e46944ebc7c42c30a4350f0
• https://git.kernel.org/stable/c/669134a66d37258e1c4a5cfbd5b82f547ae30fca
• https://git.kernel.org/stable/c/7f3b1c28e2908755fb248d3ee8ff56826f2387db
• https://git.kernel.org/stable/c/8163ea90d89b7012dd1fa4b28edf5db0c641eca7