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ext4: fix infinite loop when replaying fast_commit

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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: 8016e29f43 ("ext4: fast commit recovery path")
Signed-off-by: Luis Henriques (SUSE) <luis.henriques@linux.dev>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240515082857.32730-1-luis.henriques@linux.dev
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Luis Henriques (SUSE) 2024-05-15 09:28:57 +01:00 committed by Theodore Ts'o
parent b07855348b
commit 907c3fe532
1 changed files with 2 additions and 0 deletions
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2
fs/ext4/extents_status.c
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@ -310,6 +310,8 @@ 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;