From: Zhengchao Shao shaozhengchao@huawei.com
mainline inclusion from mainline-v5.19-rc6 commit fd1894224407c484f652ad456e1ce423e89bb3eb category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5HWKR CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=...
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Syzbot found an issue [1]: fq_codel_drop() try to drop a flow whitout any skbs, that is, the flow->head is null. The root cause, as the [2] says, is because that bpf_prog_test_run_skb() run a bpf prog which redirects empty skbs. So we should determine whether the length of the packet modified by bpf prog or others like bpf_prog_test is valid before forwarding it directly.
LINK: [1] https://syzkaller.appspot.com/bug?id=0b84da80c2917757915afa89f7738a9d16ec96c... LINK: [2] https://www.spinics.net/lists/netdev/msg777503.html
Reported-by: syzbot+7a12909485b94426aceb@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao shaozhengchao@huawei.com Reviewed-by: Stanislav Fomichev sdf@google.com Link: https://lore.kernel.org/r/20220715115559.139691-1-shaozhengchao@huawei.com Signed-off-by: Alexei Starovoitov ast@kernel.org Reviewed-by: Wei Yongjun weiyongjun1@huawei.com Reviewed-by: Yue Haibing yuehaibing@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- include/linux/skbuff.h | 8 ++++++++ net/bpf/test_run.c | 3 +++ net/core/dev.c | 1 + 3 files changed, 12 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 68efccc15a87..72cfb047fd2c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2251,6 +2251,14 @@ static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset)
#endif /* NET_SKBUFF_DATA_USES_OFFSET */
+static inline void skb_assert_len(struct sk_buff *skb) +{ +#ifdef CONFIG_DEBUG_NET + if (WARN_ONCE(!skb->len, "%s\n", __func__)) + DO_ONCE_LITE(skb_dump, KERN_ERR, skb, false); +#endif /* CONFIG_DEBUG_NET */ +} + /* * Add data to an sk_buff */ diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 99712d35e535..f266a9453c8e 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -398,6 +398,9 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) { struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;
+ if (!skb->len) + return -EINVAL; + if (!__skb) return 0;
diff --git a/net/core/dev.c b/net/core/dev.c index 12089c484b30..8e4de36eede8 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4094,6 +4094,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) bool again = false;
skb_reset_mac_header(skb); + skb_assert_len(skb);
if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP)) __skb_tstamp_tx(skb, NULL, skb->sk, SCM_TSTAMP_SCHED);