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authorXie He <xie.he.0141@gmail.com>2021-02-01 08:57:06 +0300
committerJakub Kicinski <kuba@kernel.org>2021-02-02 19:40:48 +0300
commit88c7a9fd9bdd3e453f04018920964c6f848a591a (patch)
treec23e141783bf91569d06000f5c3c26153b9ecbb5 /net/lapb
parentf418bad6ccfa6f0ef6ebc783ba72bb9c5738574f (diff)
downloadlinux-88c7a9fd9bdd3e453f04018920964c6f848a591a.tar.xz
net: lapb: Copy the skb before sending a packet
When sending a packet, we will prepend it with an LAPB header. This modifies the shared parts of a cloned skb, so we should copy the skb rather than just clone it, before we prepend the header. In "Documentation/networking/driver.rst" (the 2nd point), it states that drivers shouldn't modify the shared parts of a cloned skb when transmitting. The "dev_queue_xmit_nit" function in "net/core/dev.c", which is called when an skb is being sent, clones the skb and sents the clone to AF_PACKET sockets. Because the LAPB drivers first remove a 1-byte pseudo-header before handing over the skb to us, if we don't copy the skb before prepending the LAPB header, the first byte of the packets received on AF_PACKET sockets can be corrupted. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Xie He <xie.he.0141@gmail.com> Acked-by: Martin Schiller <ms@dev.tdt.de> Link: https://lore.kernel.org/r/20210201055706.415842-1-xie.he.0141@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/lapb')
-rw-r--r--net/lapb/lapb_out.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/lapb/lapb_out.c b/net/lapb/lapb_out.c
index 7a4d0715d1c3..a966d29c772d 100644
--- a/net/lapb/lapb_out.c
+++ b/net/lapb/lapb_out.c
@@ -82,7 +82,8 @@ void lapb_kick(struct lapb_cb *lapb)
skb = skb_dequeue(&lapb->write_queue);
do {
- if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
+ skbn = skb_copy(skb, GFP_ATOMIC);
+ if (!skbn) {
skb_queue_head(&lapb->write_queue, skb);
break;
}