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Date: Thu, 25 Apr 2024 18:04:48 +0100
From: Matthew Wilcox <willy@infradead.org>
To: Jeongjun Park <aha310510@gmail.com>
Cc: brauner@kernel.org, jfs-discussion@lists.sourceforge.net,
	jlayton@kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, shaggy@kernel.org,
	syzbot+241c815bda521982cb49@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] jfs: Fix array-index-out-of-bounds in diFree
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 <20240425142434.47481-1-aha310510@gmail.com>
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On Thu, Apr 25, 2024 at 11:24:34PM +0900, Jeongjun Park wrote:
> Matthew Wilcox wrote:
> > It should be checked earlier than this.  There's this code in
> > dbMount().  Why isn't this catching it?
> 
> This vulnerability occurs because a very large value can be passed 
> to iagp->agstart. So that code doesn't prevent the vulnerability.

In your earlier mail, you said the large value was found in db_agl2size.
If the problem is in agstart then diRead() is the right place to check it.