[PATCH v3] fs/exfat: resolve memory leak from exfat_create_upcase_table()

[Daniel Yang <danielyangkang@gmail.com>]

    If exfat_load_upcase_table reaches end and returns -EINVAL,
    allocated memory doesn't get freed and while
    exfat_load_default_upcase_table allocates more memory, leading to a    
    memory leak.
    
    Here's link to syzkaller crash report illustrating this issue:
    https://syzkaller.appspot.com/text?tag=CrashReport&x=1406c201980000

Signed-off-by: Daniel Yang <danielyangkang@gmail.com>
Reported-by: syzbot+e1c69cadec0f1a078e3d@syzkaller.appspotmail.com
---
V2 -> V3: free(NULL) is no-op, removed if() check
V1 -> V2: Moved the mem free to create_upcase_table

 fs/exfat/nls.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index afdf13c34..1ac011088 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -779,8 +779,11 @@ int exfat_create_upcase_table(struct super_block *sb)
 				le32_to_cpu(ep->dentry.upcase.checksum));
 
 			brelse(bh);
-			if (ret && ret != -EIO)
+			if (ret && ret != -EIO) {
+				/* free memory from exfat_load_upcase_table call */
+				exfat_free_upcase_table(sbi);
 				goto load_default;
+			}
 
 			/* load successfully */
 			return ret;
-- 
2.39.2