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From:   Lizhi Xu <lizhi.xu@windriver.com>
To:     <syzbot+32d3767580a1ea339a81@syzkaller.appspotmail.com>
CC:     <linux-fsdevel@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <phillip@squashfs.org.uk>, <squashfs-devel@lists.sourceforge.net>,
        <syzkaller-bugs@googlegroups.com>
Subject: [PATCH] squashfs: squashfs_read_data need to check if the length is 0
Date:   Thu, 16 Nov 2023 11:13:52 +0800
Message-ID: <20231116031352.40853-1-lizhi.xu@windriver.com>
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when the length passed in is 0, the subsequent process should be exited.

Reported-by: syzbot+32d3767580a1ea339a81@syzkaller.appspotmail.com
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
---
 fs/squashfs/block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index 581ce9519339..2dc730800f44 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -321,7 +321,7 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
 		TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2,
 		      compressed ? "" : "un", length);
 	}
-	if (length < 0 || length > output->length ||
+	if (length <= 0 || length > output->length ||
 			(index + length) > msblk->bytes_used) {
 		res = -EIO;
 		goto out;
-- 
2.25.1