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authorJon Paul Maloy <jon.maloy@ericsson.com>2014-07-25 20:48:09 +0200
committerDavid S. Miller <davem@davemloft.net>2014-07-29 03:34:01 +0200
commit13e9b9972fa0f34059e737ae215a26e43966b46f (patch)
treec028b77384eec9c472b2a11bd41c3fa70d65e93a
parentMerge tag 'master-2014-07-25' of git://git.kernel.org/pub/scm/linux/kernel/gi... (diff)
downloadlinux-13e9b9972fa0f34059e737ae215a26e43966b46f.tar.xz
linux-13e9b9972fa0f34059e737ae215a26e43966b46f.zip
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 <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/tipc/msg.c29
1 files changed, 21 insertions, 8 deletions
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);