On 6/25/25 01:09, Abinash Singh wrote:
> 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+b8c1d60e95df65e82...@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=b8c1d60e95df65e827d4
> Fixes: a28ef1f5aebe ("f2fs: maintain extent cache in separated file")
Should use this instead?
Fixes: 94afd6d6e525 ("f2fs: extent cache: support unaligned extent")
Reviewed-by: Chao Yu <c...@kernel.org>
Thanks,
> Signed-off-by: Abinash Singh <abinashsinghlalo...@gmail.com>
> ---
> v3 : Added Fixes and Closes tags
> ---
> 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 cfe925a3d555..4ce19a310f38 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -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 */
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
