[PATCH 5.10 087/352] ext4: fix infinite loop when replaying fast_commit

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5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Luis Henriques (SUSE) <luis.henriques@xxxxxxxxx>

[ Upstream commit 907c3fe532253a6ef4eb9c4d67efb71fab58c706 ]

When doing fast_commit replay an infinite loop may occur due to an
uninitialized extent_status struct.  ext4_ext_determine_insert_hole() does
not detect the replay and calls ext4_es_find_extent_range(), which will
return immediately without initializing the 'es' variable.

Because 'es' contains garbage, an integer overflow may happen causing an
infinite loop in this function, easily reproducible using fstest generic/039.

This commit fixes this issue by unconditionally initializing the structure
in function ext4_es_find_extent_range().

Thanks to Zhang Yi, for figuring out the real problem!

Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
Signed-off-by: Luis Henriques (SUSE) <luis.henriques@xxxxxxxxx>
Reviewed-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
Link: https://patch.msgid.link/20240515082857.32730-1-luis.henriques@xxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/ext4/extents_status.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index f37e62546745b..be3b3ccbf70b6 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -312,6 +312,8 @@ void ext4_es_find_extent_range(struct inode *inode,
 			       ext4_lblk_t lblk, ext4_lblk_t end,
 			       struct extent_status *es)
 {
+	es->es_lblk = es->es_len = es->es_pblk = 0;
+
 	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
 		return;
 
-- 
2.43.0







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