linux-kernel - Re: [PATCH net] xfrm: prevent some integer overflows in verify

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <053456e5-56e7-478b-b73e-96b7c2098d07@stanley.mountain>
Date: Tue, 17 Dec 2024 15:32:31 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Steffen Klassert <steffen.klassert@...unet.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net] xfrm: prevent some integer overflows in verify_
 functions

On Tue, Dec 17, 2024 at 08:03:38PM +0800, Herbert Xu wrote:
> On Tue, Dec 17, 2024 at 11:42:31AM +0300, Dan Carpenter wrote:
> >
> > +	if (algp->alg_key_len > INT_MAX) {
> 
> Why not check for UINT_MAX - 7? INT_MAX seems a bit arbitrary.
> 

That seems like basic algebra but we have a long history of getting
integer overflow checks wrong so these days I like to just use
INT_MAX where ever I can.  I wanted to use USHRT_MAX. We aren't allowed
to use more than USHRT_MAX bytes, but maybe we're allowed USHRT_MAX
bits, so I didn't do that.

regards,
dan carpenter