From: Deepanshu Kartikey <kartikey406@gmail.com> mainline inclusion from mainline-v6.19-rc1 commit 892e1cf17555735e9d021ab036c36bc7b58b0e3b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IDDF27 CVE: CVE-2025-68264 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The cached ei->i_inline_size can become stale between the initial size check and when ext4_update_inline_data()/ext4_create_inline_data() use it. Although ext4_get_max_inline_size() reads the correct value at the time of the check, concurrent xattr operations can modify i_inline_size before ext4_write_lock_xattr() is acquired. This causes ext4_update_inline_data() and ext4_create_inline_data() to work with stale capacity values, leading to a BUG_ON() crash in ext4_write_inline_data(): kernel BUG at fs/ext4/inline.c:1331! BUG_ON(pos + len > EXT4_I(inode)->i_inline_size); The race window: 1. ext4_get_max_inline_size() reads i_inline_size = 60 (correct) 2. Size check passes for 50-byte write 3. [Another thread adds xattr, i_inline_size changes to 40] 4. ext4_write_lock_xattr() acquires lock 5. ext4_update_inline_data() uses stale i_inline_size = 60 6. Attempts to write 50 bytes but only 40 bytes actually available 7. BUG_ON() triggers Fix this by recalculating i_inline_size via ext4_find_inline_data_nolock() immediately after acquiring xattr_sem. This ensures ext4_update_inline_data() and ext4_create_inline_data() work with current values that are protected from concurrent modifications. This is similar to commit a54c4613dac1 ("ext4: fix race writing to an inline_data file while its xattrs are changing") which fixed i_inline_off staleness. This patch addresses the related i_inline_size staleness issue. Reported-by: syzbot+f3185be57d7e8dda32b8@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=f3185be57d7e8dda32b8 Cc: stable@kernel.org Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com> Message-ID: <20251020060936.474314-1-kartikey406@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Yongjian Sun <sunyongjian1@huawei.com> --- fs/ext4/inline.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index bc6960c30a03..0cb175a1abe0 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -413,7 +413,12 @@ static int ext4_prepare_inline_data(handle_t *handle, struct inode *inode, return -ENOSPC; ext4_write_lock_xattr(inode, &no_expand); - + /* + * ei->i_inline_size may have changed since the initial check + * if other xattrs were added. Recalculate to ensure + * ext4_update_inline_data() validates against current capacity. + */ + (void) ext4_find_inline_data_nolock(inode); if (ei->i_inline_off) ret = ext4_update_inline_data(handle, inode, len); else -- 2.39.2