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From: Jeongjun Park <aha310510@gmail.com>
To: willy@infradead.org
Cc: brauner@kernel.org,
	jfs-discussion@lists.sourceforge.net,
	jlayton@kernel.org,
	linux-fsdevel@vger.kernel.org,
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	syzbot+241c815bda521982cb49@syzkaller.appspotmail.com,
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	Jeongjun Park <aha310510@gmail.com>
Subject: Re: [PATCH] jfs: Fix array-index-out-of-bounds in diFree
Date: Thu, 25 Apr 2024 23:37:55 +0900
Message-Id: <20240425143755.47655-1-aha310510@gmail.com>
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Matthew Wilcox wrote:
> It should be checked earlier than this.  There's this code in
> dbMount().  Why isn't this catching it?

Send final patch. With the patch that modified the location of 
release_metapage(), out-of-bounds vulnerabilities can now be 
sufficiently prevented.

Reported-by: syzbot+241c815bda521982cb49@syzkaller.appspotmail.com
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
 fs/jfs/jfs_imap.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 2ec35889ad24..cad1798dc892 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -290,7 +290,7 @@ int diSync(struct inode *ipimap)
 int diRead(struct inode *ip)
 {
 	struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
-	int iagno, ino, extno, rc;
+	int iagno, ino, extno, rc, agno;
 	struct inode *ipimap;
 	struct dinode *dp;
 	struct iag *iagp;
@@ -339,8 +339,11 @@ int diRead(struct inode *ip)
 
 	/* get the ag for the iag */
 	agstart = le64_to_cpu(iagp->agstart);
+	agno = BLKTOAG(agstart, JFS_SBI(ip->i_sb));
 
 	release_metapage(mp);
+	if(agno >= MAXAG || agno < 0)
+		return -EIO;
 
 	rel_inode = (ino & (INOSPERPAGE - 1));
 	pageno = blkno >> sbi->l2nbperpage;
-- 
2.34.1