netdev - Re: [PATCH 2/4] tipc: Fix bugs in tipc_msg

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Date:	Thu, 28 Oct 2010 10:19:33 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	allan.stephens@...driver.com, drosenberg@...curity.com,
	jon.maloy@...csson.com, torvalds@...ux-foundation.org,
	security@...nel.org
Subject: Re: [PATCH 2/4] tipc: Fix bugs in tipc_msg_build()

On Wed, Oct 27, 2010 at 03:29:31PM -0400, Paul Gortmaker wrote:
> From: Allan Stephens <Allan.Stephens@...driver.com>
> 
> Enhances TIPC's creation of message buffers so that it works properly
> when large amounts of data are involved. Calculations are now done
> using "size_t" where needed, and comparisons no longer mix signed and
> unsigned size values.
> 
> Signed-off-by: Allan Stephens <Allan.Stephens@...driver.com>
> ---
>  net/tipc/msg.c |   25 +++++++++++++++++--------
>  net/tipc/msg.h |    4 ++--
>  2 files changed, 19 insertions(+), 10 deletions(-)
> 
> diff --git a/net/tipc/msg.c b/net/tipc/msg.c
> index 38360a9..b67e831 100644
> --- a/net/tipc/msg.c
> +++ b/net/tipc/msg.c
> @@ -96,27 +96,36 @@ size_t tipc_msg_calc_data_size(struct iovec const *msg_sect, size_t num_sect)
>   *
>   * Note: Caller must not hold any locks in case copy_from_user() is interrupted!
>   *
> - * Returns message data size or errno
> + * If successful, creates message buffer and returns message data size
> + * (which must be <= TIPC_MAX_USER_MSG_SIZE).
> + * If fails only because message data size exceeds the specified maximum
> + * returns message data size, but doesn't created a message buffer.
> + * If fails for any other reason returns errno and doesn't create a buffer.
>   */
>  
>  int tipc_msg_build(struct tipc_msg *hdr,
> -			    struct iovec const *msg_sect, u32 num_sect,
> -			    int max_size, int usrmem, struct sk_buff** buf)
> +		   struct iovec const *msg_sect, size_t num_sect,
> +		   u32 max_size, int usrmem, struct sk_buff **buf)
>  {
> -	int dsz, sz, hsz, pos, res, cnt;
> +	size_t dsz;
> +	u32 hsz;
> +	u32 sz;
> +	size_t pos;
> +	size_t cnt;
> +	int res;
>  
>  	dsz = tipc_msg_calc_data_size(msg_sect, num_sect);
> -	if (unlikely(dsz > TIPC_MAX_USER_MSG_SIZE)) {
> +	if (unlikely(dsz > (size_t)TIPC_MAX_USER_MSG_SIZE)) {
>  		*buf = NULL;
>  		return -EINVAL;
>  	}
>  
>  	pos = hsz = msg_hdr_sz(hdr);
> -	sz = hsz + dsz;
> +	sz = hsz + (u32)dsz;
>  	msg_set_size(hdr, sz);
>  	if (unlikely(sz > max_size)) {
>  		*buf = NULL;
> -		return dsz;
> +		return (int)dsz;
Don't you want to return -ETOOBIG here, or something simmilar?  All the call
chains that I see for tipc_msg_build check for negative return codes and check
those against specific values.  Why return some random too-big-value?

>  	}
>  
>  	*buf = tipc_buf_acquire(sz);
> @@ -135,7 +144,7 @@ int tipc_msg_build(struct tipc_msg *hdr,
>  		pos += msg_sect[cnt].iov_len;
>  	}
>  	if (likely(res))
> -		return dsz;
> +		return (int)dsz;
>  
Ditto the above

>  	buf_discard(*buf);
>  	*buf = NULL;
> diff --git a/net/tipc/msg.h b/net/tipc/msg.h
> index a132800..41fb532 100644
> --- a/net/tipc/msg.h
> +++ b/net/tipc/msg.h
> @@ -713,8 +713,8 @@ void tipc_msg_init(struct tipc_msg *m, u32 user, u32 type,
>  			    u32 hsize, u32 destnode);
>  size_t tipc_msg_calc_data_size(struct iovec const *msg_sect, size_t num_sect);
>  int tipc_msg_build(struct tipc_msg *hdr,
> -			    struct iovec const *msg_sect, u32 num_sect,
> -			    int max_size, int usrmem, struct sk_buff** buf);
> +		   struct iovec const *msg_sect, size_t num_sect,
> +		   u32 max_size, int usrmem, struct sk_buff **buf);
>  
>  static inline void msg_set_media_addr(struct tipc_msg *m, struct tipc_media_addr *a)
>  {

I count 3 other callers of tipc_msg_calc_data_size (tipc_send,
tipc_forward2name, tipc_forward2port).  Where are the updates to those functions
to make the corresponding size_t adjustments
Neil

> -- 
> 1.7.1.GIT
> 
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