linux-kernel - Re: Catching use-after-free easily in linux kernel.

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Message-ID: <20250311003554.GN2023217@ZenIV>
Date: Tue, 11 Mar 2025 00:35:54 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Amit <amitchoudhary0523@...il.com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: Catching use-after-free easily in linux kernel.

On Mon, Mar 10, 2025 at 01:24:54PM +0530, Amit wrote:
> Hi,
> 
> We can catch use-after-free easily if we do the following:
> 
> kfree(x);
> (x) = NULL;
> 
> Now, if someone uses 'x' again then the kernel will crash and we will know where
> the use-after-free is happening and then we can fix it.

That assumes that no pointer is ever stored in more than one place.
Which is very clearly false.