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Merge branch 'net-af_packet-be-careful-when-expanding-mac-header-size'

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Eric Dumazet says:

====================
net: af_packet: be careful when expanding mac header size

A recent regression in af_packet needed a preliminary debug patch,
which will presumably be useful for next bugs hunting.

The af_packet fix is to make sure MAC headers are contained in
skb linear part, as GSO stack requests.

v2: CONFIG_DEBUG_NET depends on CONFIG_NET to avoid compile
   errors found by kernel bots.
====================

Link: https://lore.kernel.org/r/20220602161859.2546399-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2022-06-02 10:15:07 -07:00
commit 638696efc1
3 changed files with 13 additions and 4 deletions
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9
include/linux/skbuff.h
View File

@ -2696,7 +2696,14 @@ void *skb_pull(struct sk_buff *skb, unsigned int len);
static inline void *__skb_pull(struct sk_buff *skb, unsigned int len)
{
skb->len -= len;
BUG_ON(skb->len < skb->data_len);
if (unlikely(skb->len < skb->data_len)) {
#if defined(CONFIG_DEBUG_NET)
skb->len += len;
pr_err("__skb_pull(len=%u)\n", len);
skb_dump(KERN_ERR, skb, false);
#endif
BUG();
}
return skb->data += len;
}

2
net/Kconfig.debug
View File

@ -20,7 +20,7 @@ config NET_NS_REFCNT_TRACKER
config DEBUG_NET
bool "Add generic networking debug"
depends on DEBUG_KERNEL
depends on DEBUG_KERNEL && NET
help
Enable extra sanity checks in networking.
This is mostly used by fuzzers, but is safe to select.

6
net/packet/af_packet.c
View File

@ -1935,8 +1935,10 @@ static void packet_parse_headers(struct sk_buff *skb, struct socket *sock)
/* Move network header to the right position for VLAN tagged packets */
if (likely(skb->dev->type == ARPHRD_ETHER) &&
eth_type_vlan(skb->protocol) &&
__vlan_get_protocol(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
__vlan_get_protocol(skb, skb->protocol, &depth) != 0) {
if (pskb_may_pull(skb, depth))
skb_set_network_header(skb, depth);
}
skb_probe_transport_header(skb);
}