tpacket_fill_skb() can return a negative value (-errno) which
is stored in tp_len variable. In that case the following
condition will be (but shouldn't be) true:
tp_len > dev->mtu + dev->hard_header_len
as dev->mtu and dev->hard_header_len are both unsigned.
That may lead to just returning an incorrect EMSGSIZE errno
to the user.
Signed-off-by: Alexander Drozdov <al.droz...@gmail.com>
---
net/packet/af_packet.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c9e8741..d1d3625 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2403,7 +2403,8 @@ static int tpacket_snd(struct packet_sock *po, struct
msghdr *msg)
}
tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto,
addr, hlen);
- if (tp_len > dev->mtu + dev->hard_header_len) {
+ if (likely(tp_len >= 0) &&
+ tp_len > dev->mtu + dev->hard_header_len) {
struct ethhdr *ehdr;
/* Earlier code assumed this would be a VLAN pkt,
* double-check this now that we have the actual
--
1.9.1
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