linux-kernel - [PATCH] fix: divide error in qnx6_mmi_fill

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Message-Id: <20241104054435.291037-1-danielyangkang@gmail.com>
Date: Sun,  3 Nov 2024 21:44:34 -0800
From: Daniel Yang <danielyangkang@...il.com>
To: "GitAuthor: Daniel Yang" <danielyangkang@...il.com>,
	linux-kernel@...r.kernel.org (open list)
Cc: syzbot+6a0633f11d3fb88860bf@...kaller.appspotmail.com
Subject: [PATCH] fix: divide error in qnx6_mmi_fill_super

Add a check for sb_blocksize before dividing.

Signed-off-by: Daniel Yang <danielyangkang@...il.com>
Reported-by: syzbot+6a0633f11d3fb88860bf@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6a0633f11d3fb88860bf
---
 fs/qnx6/super_mmi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/qnx6/super_mmi.c b/fs/qnx6/super_mmi.c
index d282c2c73..57f34320b 100644
--- a/fs/qnx6/super_mmi.c
+++ b/fs/qnx6/super_mmi.c
@@ -65,8 +65,13 @@ struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
 	}
 
 	/* calculate second superblock blocknumber */
+	__u32 sb1_blocksize = fs32_to_cpu(sbi, sb1->sb_blocksize);
+
+	if (!sb1_blocksize) {
+		pr_err("superblock #1 blocksize 0\n");
+		goto out;
+	}
 	offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
-					fs32_to_cpu(sbi, sb1->sb_blocksize);
+								sb1_blocksize;
 
 	/* set new blocksize */
 	if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
-- 
2.39.2