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f2fs: fix KMSAN uninit-value in extent_info usage

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KMSAN reported a use of uninitialized value in `__is_extent_mergeable()`
 and `__is_back_mergeable()` via the read extent tree path.

The root cause is that `get_read_extent_info()` only initializes three
fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the
remaining fields uninitialized. This leads to undefined behavior
when those fields are accessed later, especially during
extent merging.

Fix it by zero-initializing the `extent_info` struct before population.

Reported-by: syzbot+b8c1d60e95df65e827d4@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b8c1d60e95df65e827d4
Fixes: 94afd6d6e5 ("f2fs: extent cache: support unaligned extent")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Abinash Singh <abinashsinghlalotra@gmail.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Abinash Singh 2025-06-25 16:35:37 +05:30 committed by Jaegeuk Kim
parent 90c5ce37ad
commit 154467f4ad
1 changed files with 1 additions and 1 deletions
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2
fs/f2fs/extent_cache.c
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@ -414,7 +414,7 @@ void f2fs_init_read_extent_tree(struct inode *inode, struct folio *ifolio)
struct f2fs_extent *i_ext = &F2FS_INODE(&ifolio->page)->i_ext;
struct extent_tree *et;
struct extent_node *en;
struct extent_info ei;
struct extent_info ei = {0};
if (!__may_extent_tree(inode, EX_READ)) {
/* drop largest read extent */