6.12-stable review patch. If anyone has any objections, please let me know.
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From: Abinash Singh abinashlalotra@gmail.com
[ Upstream commit 154467f4ad033473e5c903a03e7b9bca7df9a0fa ]
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: 94afd6d6e525 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/extent_cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c index fb09c8e9bc57..2ccc86875099 100644 --- a/fs/f2fs/extent_cache.c +++ b/fs/f2fs/extent_cache.c @@ -381,7 +381,7 @@ void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage) struct f2fs_extent *i_ext = &F2FS_INODE(ipage)->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 */