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authorJohn Fastabend <john.fastabend@gmail.com>2018-07-05 08:49:59 -0700
committerAlexei Starovoitov <ast@kernel.org>2018-07-07 15:19:29 -0700
commit0c6bc6e531a6db36f49622f1f115770160f7afb0 (patch)
tree77b565cda20fbeeec014f9d7c63b48d1b9c14505 /net/core
parent631da8534aeea2e2f8b36a832d065a203f24fa43 (diff)
downloadlinux-0c6bc6e531a6db36f49622f1f115770160f7afb0.tar.bz2
bpf: fix sk_skb programs without skb->dev assigned
Multiple BPF helpers in use by sk_skb programs calculate the max skb length using the __bpf_skb_max_len function. However, this calculates the max length using the skb->dev pointer which can be NULL when an sk_skb program is paired with an sk_msg program. To force this a sk_msg program needs to redirect into the ingress path of a sock with an attach sk_skb program. Then the the sk_skb program would need to call one of the helpers that adjust the skb size. To fix the null ptr dereference use SKB_MAX_ALLOC size if no dev is available. Fixes: 8934ce2fd081 ("bpf: sockmap redirect ingress support") Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/filter.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 0ca6907d7efe..3095f1ba7015 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2779,7 +2779,8 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 len_diff)
static u32 __bpf_skb_max_len(const struct sk_buff *skb)
{
- return skb->dev->mtu + skb->dev->hard_header_len;
+ return skb->dev ? skb->dev->mtu + skb->dev->hard_header_len :
+ SKB_MAX_ALLOC;
}
static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)