From: Abinash Singh Date: Wed, 25 Jun 2025 11:05:37 +0000 (+0530) Subject: f2fs: fix KMSAN uninit-value in extent_info usage X-Git-Tag: v6.1.148~62 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e68b751ec2b15d866967812c57cfdfc1eba6a269;p=thirdparty%2Fkernel%2Fstable.git f2fs: fix KMSAN uninit-value in extent_info usage [ 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 Signed-off-by: Abinash Singh Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c index f13143efc4b1c..a5c63c7da2994 100644 --- a/fs/f2fs/extent_cache.c +++ b/fs/f2fs/extent_cache.c @@ -440,7 +440,7 @@ 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 */