CCing the right stable ML address... Apologies!
On 11/05/2024 18:10, Guilherme G. Piccoli wrote:
From: Baokun Li libaokun1@huawei.com
commit d36f6ed761b53933b0b4126486c10d3da7751e7f upstream.
Hulk Robot reported a BUG_ON:
kernel BUG at fs/ext4/extents_status.c:199! [...] RIP: 0010:ext4_es_end fs/ext4/extents_status.c:199 [inline] RIP: 0010:__es_tree_search+0x1e0/0x260 fs/ext4/extents_status.c:217 [...] Call Trace: ext4_es_cache_extent+0x109/0x340 fs/ext4/extents_status.c:766 ext4_cache_extents+0x239/0x2e0 fs/ext4/extents.c:561 ext4_find_extent+0x6b7/0xa20 fs/ext4/extents.c:964 ext4_ext_map_blocks+0x16b/0x4b70 fs/ext4/extents.c:4384 ext4_map_blocks+0xe26/0x19f0 fs/ext4/inode.c:567 ext4_getblk+0x320/0x4c0 fs/ext4/inode.c:980 ext4_bread+0x2d/0x170 fs/ext4/inode.c:1031 ext4_quota_read+0x248/0x320 fs/ext4/super.c:6257 v2_read_header+0x78/0x110 fs/quota/quota_v2.c:63 v2_check_quota_file+0x76/0x230 fs/quota/quota_v2.c:82 vfs_load_quota_inode+0x5d1/0x1530 fs/quota/dquot.c:2368 dquot_enable+0x28a/0x330 fs/quota/dquot.c:2490 ext4_quota_enable fs/ext4/super.c:6137 [inline] ext4_enable_quotas+0x5d7/0x960 fs/ext4/super.c:6163 ext4_fill_super+0xa7c9/0xdc00 fs/ext4/super.c:4754 mount_bdev+0x2e9/0x3b0 fs/super.c:1158 mount_fs+0x4b/0x1e4 fs/super.c:1261 [...] ==================================================================
Above issue may happen as follows:
ext4_fill_super ext4_enable_quotas ext4_quota_enable ext4_iget __ext4_iget ext4_ext_check_inode ext4_ext_check __ext4_ext_check ext4_valid_extent_entries Check for overlapping extents does't take effect dquot_enable vfs_load_quota_inode v2_check_quota_file v2_read_header ext4_quota_read ext4_bread ext4_getblk ext4_map_blocks ext4_ext_map_blocks ext4_find_extent ext4_cache_extents ext4_es_cache_extent ext4_es_cache_extent __es_tree_search ext4_es_end BUG_ON(es->es_lblk + es->es_len < es->es_lblk)
The error ext4 extents is as follows: 0af3 0300 0400 0000 00000000 extent_header 00000000 0100 0000 12000000 extent1 00000000 0100 0000 18000000 extent2 02000000 0400 0000 14000000 extent3
In the ext4_valid_extent_entries function, if prev is 0, no error is returned even if lblock<=prev. This was intended to skip the check on the first extent, but in the error image above, prev=0+1-1=0 when checking the second extent, so even though lblock<=prev, the function does not return an error. As a result, bug_ON occurs in __es_tree_search and the system panics.
To solve this problem, we only need to check that:
- The lblock of the first extent is not less than 0.
- The lblock of the next extent is not less than the next block of the previous extent.
The same applies to extent_idx.
Cc: stable@kernel.org Fixes: 5946d089379a ("ext4: check for overlapping extents in ext4_valid_extent_entries()") Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20220518120816.1541863-1-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Reported-by: syzbot+2a58d88f0fb315c85363@syzkaller.appspotmail.com [gpiccoli: Manual backport due to unrelated missing patches.] Signed-off-by: Guilherme G. Piccoli gpiccoli@igalia.com
Hey folks, this one should have been backported but due to merge issues [0], it ended-up not being on 5.4.y . So here is a working version! Cheers,
Guilherme
[0] https://lore.kernel.org/stable/165451751147179@kroah.com/
fs/ext4/extents.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 98e1b1ddb4ec..90b12c7c0f20 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -409,7 +409,7 @@ static int ext4_valid_extent_entries(struct inode *inode, { unsigned short entries; ext4_lblk_t lblock = 0;
- ext4_lblk_t prev = 0;
- ext4_lblk_t cur = 0;
if (eh->eh_entries == 0) return 1; @@ -435,12 +435,12 @@ static int ext4_valid_extent_entries(struct inode *inode, /* Check for overlapping extents */ lblock = le32_to_cpu(ext->ee_block);
if ((lblock <= prev) && prev) {
if (lblock < cur) { pblock = ext4_ext_pblock(ext); es->s_last_error_block = cpu_to_le64(pblock); return 0; }
prev = lblock + ext4_ext_get_actual_len(ext) - 1;
cur = lblock + ext4_ext_get_actual_len(ext); ext++; entries--;@@ -460,13 +460,13 @@ static int ext4_valid_extent_entries(struct inode *inode, /* Check for overlapping index extents */ lblock = le32_to_cpu(ext_idx->ei_block);
if ((lblock <= prev) && prev) {
if (lblock < cur) { *pblk = ext4_idx_pblock(ext_idx); return 0; } ext_idx++; entries--;
prev = lblock;
cur = lblock + 1;