ocfs2: reject inconsistent local xattr entries

[BUG]
A corrupt OCFS2 xattr entry can set OCFS2_XATTR_ENTRY_LOCAL while
keeping xe_value_size larger than OCFS2_XATTR_INLINE_SIZE. When that
entry reaches namevalue_size_xe(), the filesystem hits its BUG_ON:

kernel BUG at fs/ocfs2/xattr.c:231!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
RIP: 0010:namevalue_size_xe fs/ocfs2/xattr.c:231 [inline]
RIP: 0010:ocfs2_xa_block_wipe_namevalue+0x2e4/0x330 fs/ocfs2/xattr.c:1638
Call Trace:
 ocfs2_xa_wipe_namevalue fs/ocfs2/xattr.c:1470 [inline]
 ocfs2_xa_remove_entry+0xae/0x1d0 fs/ocfs2/xattr.c:1941
 ocfs2_xa_remove fs/ocfs2/xattr.c:2043 [inline]
 ocfs2_xa_set+0x11a8/0x30a0 fs/ocfs2/xattr.c:2247
 ocfs2_xattr_ibody_set+0x302/0xc50 fs/ocfs2/xattr.c:2795
 __ocfs2_xattr_set_handle+0x7e6/0xdb0 fs/ocfs2/xattr.c:3416
 ocfs2_xattr_set+0x1447/0x2610 fs/ocfs2/xattr.c:3650
 ocfs2_xattr_security_set+0x37/0x50 fs/ocfs2/xattr.c:7241
 __vfs_removexattr+0x14d/0x1d0 fs/xattr.c:518
 cap_inode_killpriv+0x29/0x50 security/commoncap.c:355
 security_inode_killpriv+0x105/0x220 security/security.c:2724
 setattr_prepare+0x147/0x8a0 fs/attr.c:219
 ocfs2_setattr+0x504/0x1fd0 fs/ocfs2/file.c:1148
 notify_change+0x4b5/0x1030 fs/attr.c:546
 do_truncate+0x1d2/0x230 fs/open.c:68
 handle_truncate fs/namei.c:3596 [inline]
 do_open fs/namei.c:3979 [inline]
 path_openat+0x260f/0x2ce0 fs/namei.c:4134
 do_filp_open+0x1f6/0x430 fs/namei.c:4161
 do_sys_openat2+0x117/0x1c0 fs/open.c:1437
 ...

[CAUSE]
namevalue_size_xe() assumes that local entries contain an inline value
no larger than OCFS2_XATTR_INLINE_SIZE. Existing xattr metadata
validation only checks whether the value fits the storage region, and
cached entries can reach lookup and bucket maintenance paths without a
semantic check. A corrupt entry can therefore be passed to
namevalue_size_xe().

[FIX]
Validate the local/value-size invariant in the existing flat and bucket
metadata validators and before accepting matched entries or traversing
bucket entries in paths that call namevalue_size_xe(). Return an OCFS2
corruption error instead of firing the assertion.

Link: https://lore.kernel.org/20260806085012.2650042-1-gality369@gmail.com
Signed-off-by: ZhengYuan Huang <gality369@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions