linux-kernel - Re: [PATCH v2] nfsd: prevent integer overflow in decode_cb

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: <3d02547428c59083880e1e0c0d38fe83d87c1fde.camel@kernel.org>
Date: Thu, 19 Sep 2024 10:44:51 +0200
From: Jeff Layton <jlayton@...nel.org>
To: Dan Carpenter <dan.carpenter@...aro.org>, Chuck Lever
	 <chuck.lever@...cle.com>
Cc: Neil Brown <neilb@...e.de>, Olga Kornievskaia <okorniev@...hat.com>, Dai
 Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
 linux-nfs@...r.kernel.org,  linux-kernel@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] nfsd: prevent integer overflow in
 decode_cb_compound4res()

On Thu, 2024-09-19 at 11:12 +0300, Dan Carpenter wrote:
> If "length" is >= U32_MAX - 3 then the "length + 4" addition can result
> in an integer overflow.  The impact of this bug is not totally clear to
> me, but it's safer to not allow the integer overflow.
> 
> Check that "length" is valid right away before doing any math.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
> v2: Check that "len" is valid instead of just checking for integer
>     overflows.
> 
>  fs/nfsd/nfs4callback.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 43b8320c8255..0f5b7b6fba74 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -317,6 +317,8 @@ static int decode_cb_compound4res(struct xdr_stream *xdr,
>  	hdr->status = be32_to_cpup(p++);
>  	/* Ignore the tag */
>  	length = be32_to_cpup(p++);
> +	if (unlikely(length > xdr->buf->len))
> +		goto out_overflow;
>  	p = xdr_inline_decode(xdr, length + 4);
>  	if (unlikely(p == NULL))
>  		goto out_overflow;

Reviewed-by: Jeff Layton <jlayton@...nel.org>