Re: [PATCH] sctp: fix append error cause to ERROR chunk correctly

[Neil Horman <nhorman@xxxxxxxxxxxxx>]

On Thu, May 13, 2010 at 01:19:29PM +0800, Wei Yongjun wrote:
> commit 5fa782c2f5ef6c2e4f04d3e228412c9b4a4c8809
>   sctp: Fix skb_over_panic resulting from multiple invalid \
>     parameter errors (CVE-2010-1173) (v4)
> 
> cause 'error cause' never be add the the ERROR chunk due to
> some typo when check valid length in sctp_init_cause_fixed().
> 
> Signed-off-by: Wei Yongjun <yjwei@xxxxxxxxxxxxxx>
> ---
>  net/sctp/sm_make_chunk.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
> index 30c1767..70d6c10 100644
> --- a/net/sctp/sm_make_chunk.c
> +++ b/net/sctp/sm_make_chunk.c
> @@ -141,7 +141,7 @@ int sctp_init_cause_fixed(struct sctp_chunk *chunk, __be16 cause_code,
>  	len = sizeof(sctp_errhdr_t) + paylen;
>  	err.length  = htons(len);
>  
> -	if (skb_tailroom(chunk->skb) >  len)
> +	if (skb_tailroom(chunk->skb) < len)
>  		return -ENOSPC;
>  	chunk->subh.err_hdr = sctp_addto_chunk_fixed(chunk,
>  						     sizeof(sctp_errhdr_t),
> @@ -1421,7 +1421,7 @@ void *sctp_addto_chunk(struct sctp_chunk *chunk, int len, const void *data)
>  void *sctp_addto_chunk_fixed(struct sctp_chunk *chunk,
>  			     int len, const void *data)
>  {
> -	if (skb_tailroom(chunk->skb) > len)
> +	if (skb_tailroom(chunk->skb) >= len)
>  		return sctp_addto_chunk(chunk, len, data);
>  	else
>  		return NULL;
Yup, thanks!
Reviewed-by: Neil Horman <nhorman@xxxxxxxxxxxxx>

> -- 
> 1.6.5.2
> 
> 
> 
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