netdev - Re: [PATCH net] net/tcp_sigpool: Fix some off by one bugs

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Date: Tue, 31 Oct 2023 16:58:43 +0000
From: Dmitry Safonov <dima@...sta.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Eric Dumazet <edumazet@...gle.com>, "David S. Miller"
 <davem@...emloft.net>, David Ahern <dsahern@...nel.org>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Steen Hegelund <Steen.Hegelund@...rochip.com>, netdev@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net] net/tcp_sigpool: Fix some off by one bugs

Hi Dan,

On 10/31/23 09:51, Dan Carpenter wrote:
> The "cpool_populated" variable is the number of elements in the cpool[]
> array that have been populated.  It is incremented in
> tcp_sigpool_alloc_ahash() every time we populate a new element.
> Unpopulated elements are NULL but if we have populated every element then
> this code will read one element beyond the end of the array.
> 
> Fixes: 8c73b26315aa ("net/tcp: Prepare tcp_md5sig_pool for TCP-AO")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>

Yeah, those are barriers for any issues in the caller-code, so that's
not too critical but nice to have. Thanks for the patch!

Reviewed-by: Dmitry Safonov <dima@...sta.com>

> ---
> From static analysis and review.
> 
>  net/ipv4/tcp_sigpool.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ipv4/tcp_sigpool.c b/net/ipv4/tcp_sigpool.c
> index 65a8eaae2fec..55b310a722c7 100644
> --- a/net/ipv4/tcp_sigpool.c
> +++ b/net/ipv4/tcp_sigpool.c
> @@ -231,7 +231,7 @@ static void cpool_schedule_cleanup(struct kref *kref)
>   */
>  void tcp_sigpool_release(unsigned int id)
>  {
> -	if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
> +	if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
>  		return;
>  
>  	/* slow-path */
> @@ -245,7 +245,7 @@ EXPORT_SYMBOL_GPL(tcp_sigpool_release);
>   */
>  void tcp_sigpool_get(unsigned int id)
>  {
> -	if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
> +	if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
>  		return;
>  	kref_get(&cpool[id].kref);
>  }
> @@ -256,7 +256,7 @@ int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c) __cond_acquires(RC
>  	struct crypto_ahash *hash;
>  
>  	rcu_read_lock_bh();
> -	if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg)) {
> +	if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg)) {
>  		rcu_read_unlock_bh();
>  		return -EINVAL;
>  	}
> @@ -301,7 +301,7 @@ EXPORT_SYMBOL_GPL(tcp_sigpool_end);
>   */
>  size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len)
>  {
> -	if (WARN_ON_ONCE(id > cpool_populated || !cpool[id].alg))
> +	if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
>  		return -EINVAL;
>  
>  	return strscpy(buf, cpool[id].alg, buf_len);

Thanks,
            Dmitry