diff options
| author | Joseph Qi <joseph.qi@linux.alibaba.com> | 2026-04-03 14:38:30 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-04-06 11:13:43 -0700 |
| commit | 7bc5da4842bed3252d26e742213741a4d0ac1b14 (patch) | |
| tree | 544c61c8e7b74d062b19ad5d7031769200cdad67 | |
| parent | 4c04c6b47c361612b1d70cec8f7a60b1482d1400 (diff) | |
ocfs2: fix out-of-bounds write in ocfs2_write_end_inline
KASAN reports a use-after-free write of 4086 bytes in
ocfs2_write_end_inline, called from ocfs2_write_end_nolock during a
copy_file_range splice fallback on a corrupted ocfs2 filesystem mounted on
a loop device. The actual bug is an out-of-bounds write past the inode
block buffer, not a true use-after-free. The write overflows into an
adjacent freed page, which KASAN reports as UAF.
The root cause is that ocfs2_try_to_write_inline_data trusts the on-disk
id_count field to determine whether a write fits in inline data. On a
corrupted filesystem, id_count can exceed the physical maximum inline data
capacity, causing writes to overflow the inode block buffer.
Call trace (crash path):
vfs_copy_file_range (fs/read_write.c:1634)
do_splice_direct
splice_direct_to_actor
iter_file_splice_write
ocfs2_file_write_iter
generic_perform_write
ocfs2_write_end
ocfs2_write_end_nolock (fs/ocfs2/aops.c:1949)
ocfs2_write_end_inline (fs/ocfs2/aops.c:1915)
memcpy_from_folio <-- KASAN: write OOB
So add id_count upper bound check in ocfs2_validate_inode_block() to
alongside the existing i_size check to fix it.
Link: https://lkml.kernel.org/r/20260403063830.3662739-1-joseph.qi@linux.alibaba.com
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reported-by: syzbot+62c1793956716ea8b28a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=62c1793956716ea8b28a
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/ocfs2/inode.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c index 03a51662ea8e..a2ccd8011706 100644 --- a/fs/ocfs2/inode.c +++ b/fs/ocfs2/inode.c @@ -1505,6 +1505,16 @@ int ocfs2_validate_inode_block(struct super_block *sb, goto bail; } + if (le16_to_cpu(data->id_count) > + ocfs2_max_inline_data_with_xattr(sb, di)) { + rc = ocfs2_error(sb, + "Invalid dinode #%llu: inline data id_count %u exceeds max %d\n", + (unsigned long long)bh->b_blocknr, + le16_to_cpu(data->id_count), + ocfs2_max_inline_data_with_xattr(sb, di)); + goto bail; + } + if (le64_to_cpu(di->i_size) > le16_to_cpu(data->id_count)) { rc = ocfs2_error(sb, "Invalid dinode #%llu: inline data i_size %llu exceeds id_count %u\n", |