From: Brian Foster <bfoster@redhat.com> mainline inclusion from mainline-v6.16-rc1 commit e26268ff1dcae5662c1b96c35f18cfa6ab73d9de category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICK4S2 CVE: CVE-2025-38220 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- fstest generic/388 occasionally reproduces a crash that looks as follows: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... Call Trace: <TASK> ext4_block_zero_page_range+0x30c/0x380 [ext4] ext4_truncate+0x436/0x440 [ext4] ext4_process_orphan+0x5d/0x110 [ext4] ext4_orphan_cleanup+0x124/0x4f0 [ext4] ext4_fill_super+0x262d/0x3110 [ext4] get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x26/0xd0 vfs_cmd_create+0x59/0xe0 __do_sys_fsconfig+0x4ed/0x6b0 do_syscall_64+0x82/0x170 ... This occurs when processing a symlink inode from the orphan list. The partial block zeroing code in the truncate path calls ext4_dirty_journalled_data() -> folio_mark_dirty(). The latter calls mapping->a_ops->dirty_folio(), but symlink inodes are not assigned an a_ops vector in ext4, hence the crash. To avoid this problem, update the ext4_dirty_journalled_data() helper to only mark the folio dirty on regular files (for which a_ops is assigned). This also matches the journaling logic in the ext4_symlink() creation path, where ext4_handle_dirty_metadata() is called directly. Fixes: d84c9ebdac1e ("ext4: Mark pages with journalled data dirty") Signed-off-by: Brian Foster <bfoster@redhat.com> Link: https://patch.msgid.link/20250516173800.175577-1-bfoster@redhat.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Cc: stable@kernel.org Signed-off-by: Yongjian Sun <sunyongjian1@huawei.com> --- fs/ext4/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 1e27155797cc..045a7213d6b6 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1019,7 +1019,12 @@ int ext4_walk_page_buffers(handle_t *handle, struct inode *inode, */ static int ext4_dirty_journalled_data(handle_t *handle, struct buffer_head *bh) { - folio_mark_dirty(bh->b_folio); + struct folio *folio = bh->b_folio; + struct inode *inode = folio->mapping->host; + + /* only regular files have a_ops */ + if (S_ISREG(inode->i_mode)) + folio_mark_dirty(folio); return ext4_handle_dirty_metadata(handle, NULL, bh); } -- 2.39.2