sctp: fix append error cause to ERROR chunk correctly

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@cn.fujitsu.com>
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index d8261f3..bd2a50b 100644 (file)
--- 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),
@@ -1415,7 +1415,7 @@ 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;