CVE-2026-53039

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

ocfs2: validate group add input before caching

[BUG] OCFS2_IOC_GROUP_ADD can trigger a BUG_ON in ocfs2_set_new_buffer_uptodate():

kernel BUG at fs/ocfs2/uptodate.c:509! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ocfs2_set_new_buffer_uptodate+0x194/0x1e0 fs/ocfs2/uptodate.c:509 Code: ffffe88f 42b9fe4c 89e64889 dfe8b4df Call Trace: ocfs2_group_add+0x3f1/0x1510 fs/ocfs2/resize.c:507 ocfs2_ioctl+0x309/0x6e0 fs/ocfs2/ioctl.c:887 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x197/0x1e0 fs/ioctl.c:583 x64_sys_call+0x1144/0x26a0 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x93/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7bbfb55a966d

[CAUSE] ocfs2_group_add() calls ocfs2_set_new_buffer_uptodate() on a user-controlled group block before ocfs2_verify_group_and_input() validates that block number. That helper is only valid for newly allocated metadata and asserts that the block is not already present in the chosen metadata cache. The code also uses INODE_CACHE(inode) even though the group descriptor belongs to main_bm_inode and later journal accesses use that cache context instead.

[FIX] Validate the on-disk group descriptor before caching it, then add it to the metadata cache tracked by INODE_CACHE(main_bm_inode). Keep the validation failure path separate from the later cleanup path so we only remove the buffer from that cache after it has actually been inserted. This keeps the group buffer lifetime consistent across validation, journaling, and cleanup.

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/22544ddedf381ed5191cfc783aea8d6c936bc201
• https://git.kernel.org/stable/c/6c5e70409c1961fe1278968f038eaaed6cc1145a
• https://git.kernel.org/stable/c/70b672833f4025341c11b22c7f83778a5cd611bc
• https://git.kernel.org/stable/c/76bd722db0a92b84ccd99e03796a0b6f1ae71c31
• https://git.kernel.org/stable/c/aed87e866d1a321edb9703563c2faa8fec89835d
• https://git.kernel.org/stable/c/b9ae3942deec4c9e3fa2070521f90910f7490011
• https://git.kernel.org/stable/c/e7c2cb552e6eb85c0f5aefdd7f0f7c3c8591a6a3
• https://git.kernel.org/stable/c/f7e139d7563f6947ad509fb468903941d0bb7ddd