linux-kernel - [PATCH v2] fs/exfat: resolve memory leak from exfat_create_upcase

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Message-Id: <20240916052128.225475-1-danielyangkang@gmail.com>
Date: Sun, 15 Sep 2024 22:21:27 -0700
From: Daniel Yang <danielyangkang@...il.com>
To: viro@...iv.linux.org.uk,
	Namjae Jeon <linkinjeon@...nel.org>,
	Sungjong Seo <sj1557.seo@...sung.com>,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Daniel Yang <danielyangkang@...il.com>,
	syzbot+e1c69cadec0f1a078e3d@...kaller.appspotmail.com
Subject: [PATCH v2] fs/exfat: resolve memory leak from exfat_create_upcase_table()

    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@...il.com>
Reported-by: syzbot+e1c69cadec0f1a078e3d@...kaller.appspotmail.com
---
V1 -> V2: Moved the mem free to create_upcase_table

 fs/exfat/nls.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index afdf13c34..8828f9d29 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
  */
 
+#include <cerrno>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/buffer_head.h>
@@ -779,8 +780,13 @@ 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 */
+				if (ret == -EINVAL) {
+					exfat_free_upcase_table(sbi);
+				}
 				goto load_default;
+			}
 
 			/* load successfully */
 			return ret;
-- 
2.39.2