[PATCH v2] erofs-utils: sbi->devs should be cleared after freed

[Gao Xiang]

Otherwise, it could cause double-free if sbi reuses
when fuzzing [1].

[1] https://github.com/erofs/erofsnightly/actions/runs/5921003885/job/16053013007
Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
---
changes since v1:
 - add a missing sbi->devs = NULL in erofs_init_devices().

 lib/super.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/super.c b/lib/super.c
index 58e2574..38caf4d 100644
--- a/lib/super.c
+++ b/lib/super.c
@@ -53,6 +53,7 @@ static int erofs_init_devices(struct erofs_sb_info *sbi,
 		ret = dev_read(sbi, 0, &dis, pos, sizeof(dis));
 		if (ret < 0) {
 			free(sbi->devs);
+			sbi->devs = NULL;
 			return ret;
 		}
 
@@ -123,14 +124,18 @@ int erofs_read_superblock(struct erofs_sb_info *sbi)
 		return ret;
 
 	ret = erofs_xattr_prefixes_init(sbi);
-	if (ret)
+	if (ret && sbi->devs) {
 		free(sbi->devs);
+		sbi->devs = NULL;
+	}
 	return ret;
 }
 
 void erofs_put_super(struct erofs_sb_info *sbi)
 {
-	if (sbi->devs)
+	if (sbi->devs) {
 		free(sbi->devs);
+		sbi->devs = NULL;
+	}
 	erofs_xattr_prefixes_cleanup(sbi);
 }
-- 
2.24.4