From 13e9b9972fa0f34059e737ae215a26e43966b46f Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Fri, 25 Jul 2014 14:48:09 -0400 Subject: tipc: make tipc_buf_append() more robust As per comment from David Miller, we try to make the buffer reassembly function more resilient to user errors than it is today. - We check that the "*buf" parameter always is set, since this is mandatory input. - We ensure that *buf->next always is set to NULL before linking in the buffer, instead of relying of the caller to have done this. - We ensure that the "tail" pointer in the head buffer's control block is initialized to NULL when the first fragment arrives. Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/msg.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) (limited to 'net/tipc/msg.c') diff --git a/net/tipc/msg.c b/net/tipc/msg.c index b6f45d029933..9680be6d388a 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -72,27 +72,38 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf) struct sk_buff *head = *headbuf; struct sk_buff *frag = *buf; struct sk_buff *tail; - struct tipc_msg *msg = buf_msg(frag); - u32 fragid = msg_type(msg); - bool headstolen; + struct tipc_msg *msg; + u32 fragid; int delta; + bool headstolen; + if (!frag) + goto err; + + msg = buf_msg(frag); + fragid = msg_type(msg); + frag->next = NULL; skb_pull(frag, msg_hdr_sz(msg)); if (fragid == FIRST_FRAGMENT) { - if (head || skb_unclone(frag, GFP_ATOMIC)) - goto out_free; + if (unlikely(head)) + goto err; + if (unlikely(skb_unclone(frag, GFP_ATOMIC))) + goto err; head = *headbuf = frag; skb_frag_list_init(head); + TIPC_SKB_CB(head)->tail = NULL; *buf = NULL; return 0; } + if (!head) - goto out_free; - tail = TIPC_SKB_CB(head)->tail; + goto err; + if (skb_try_coalesce(head, frag, &headstolen, &delta)) { kfree_skb_partial(frag, headstolen); } else { + tail = TIPC_SKB_CB(head)->tail; if (!skb_has_frag_list(head)) skb_shinfo(head)->frag_list = frag; else @@ -102,6 +113,7 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf) head->len += frag->len; TIPC_SKB_CB(head)->tail = frag; } + if (fragid == LAST_FRAGMENT) { *buf = head; TIPC_SKB_CB(head)->tail = NULL; @@ -110,7 +122,8 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf) } *buf = NULL; return 0; -out_free: + +err: pr_warn_ratelimited("Unable to build fragment list\n"); kfree_skb(*buf); kfree_skb(*headbuf); -- cgit