5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
commit 02dffe9ab092fc4c8800aee68cb7eafd37a980c4 upstream.
There is no check if stream size and start_clu are invalid.
If start_clu is EOF cluster and stream size is 4096, It will
cause uninit value access. because ei->hint_femp.eidx could
be 128(if cluster size is 4K) and wrong hint will allocate
next cluster. and this cluster will be same with the cluster
that is allocated by exfat_extend_valid_size(). The previous
patch will check invalid start_clu, but for clarity, initialize
hint_femp.eidx to zero.
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: syzbot+01218003be74b5e1213a@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+01218003be74b5e1213a@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@xxxxxxxx>
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/exfat/namei.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -356,6 +356,7 @@ static int exfat_find_empty_entry(struct
if (ei->start_clu == EXFAT_EOF_CLUSTER) {
ei->start_clu = clu.dir;
p_dir->dir = clu.dir;
+ hint_femp.eidx = 0;
}
/* append to the FAT chain */
