This is a note to let you know that I've just added the patch titled ext4: add inode table check in __ext4_get_inode_loc to aovid possible infinite loop to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-add-inode-table-check-in-__ext4_get_inode_loc-to-aovid-possible-infinite-loop.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From eee22187b53611e173161e38f61de1c7ecbeb876 Mon Sep 17 00:00:00 2001 From: Baokun Li <libaokun1@xxxxxxxxxx> Date: Wed, 17 Aug 2022 21:27:01 +0800 Subject: ext4: add inode table check in __ext4_get_inode_loc to aovid possible infinite loop From: Baokun Li <libaokun1@xxxxxxxxxx> commit eee22187b53611e173161e38f61de1c7ecbeb876 upstream. In do_writepages, if the value returned by ext4_writepages is "-ENOMEM" and "wbc->sync_mode == WB_SYNC_ALL", retry until the condition is not met. In __ext4_get_inode_loc, if the bh returned by sb_getblk is NULL, the function returns -ENOMEM. In __getblk_slow, if the return value of grow_buffers is less than 0, the function returns NULL. When the three processes are connected in series like the following stack, an infinite loop may occur: do_writepages <--- keep retrying ext4_writepages mpage_map_and_submit_extent mpage_map_one_extent ext4_map_blocks ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_ext_convert_to_initialized ext4_split_extent ext4_split_extent_at __ext4_ext_dirty __ext4_mark_inode_dirty ext4_reserve_inode_write ext4_get_inode_loc __ext4_get_inode_loc <--- return -ENOMEM sb_getblk __getblk_gfp __getblk_slow <--- return NULL grow_buffers grow_dev_page <--- return -ENXIO ret = (block < end_block) ? 1 : -ENXIO; In this issue, bg_inode_table_hi is overwritten as an incorrect value. As a result, `block < end_block` cannot be met in grow_dev_page. Therefore, __ext4_get_inode_loc always returns '-ENOMEM' and do_writepages keeps retrying. As a result, the writeback process is in the D state due to an infinite loop. Add a check on inode table block in the __ext4_get_inode_loc function by referring to ext4_read_inode_bitmap to avoid this infinite loop. Cc: stable@xxxxxxxxxx Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx> Link: https://lore.kernel.org/r/20220817132701.3015912-3-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inode.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4663,9 +4663,17 @@ static int __ext4_get_inode_loc(struct i inodes_per_block = EXT4_SB(sb)->s_inodes_per_block; inode_offset = ((inode->i_ino - 1) % EXT4_INODES_PER_GROUP(sb)); - block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block); iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb); + block = ext4_inode_table(sb, gdp); + if ((block <= le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) || + (block >= ext4_blocks_count(EXT4_SB(sb)->s_es))) { + ext4_error(sb, "Invalid inode table block %llu in " + "block_group %u", block, iloc->block_group); + return -EFSCORRUPTED; + } + block += (inode_offset / inodes_per_block); + bh = sb_getblk(sb, block); if (unlikely(!bh)) return -ENOMEM; Patches currently in stable-queue which might be from libaokun1@xxxxxxxxxx are queue-4.19/ext4-fix-bug_on-in-__es_tree_search-caused-by-bad-boot-loader-inode.patch queue-4.19/ext4-add-inode-table-check-in-__ext4_get_inode_loc-to-aovid-possible-infinite-loop.patch queue-4.19/ext4-add-helper-to-check-quota-inums.patch