forked from Minki/linux
decnet: dn_rtmsg: Improve input length sanitization in dnrmg_receive_user_skb
Verify that the length of the socket buffer is sufficient to cover the entire nlh->nlmsg_len field before accessing that field for further input sanitization. If the client only supplies 1-3 bytes of data in sk_buff, then nlh->nlmsg_len remains partially uninitialized and contains leftover memory from the corresponding kernel allocation. Operating on such data may result in indeterminate evaluation of the nlmsg_len < sizeof(*nlh) expression. The bug was discovered by a runtime instrumentation designed to detect use of uninitialized memory in the kernel. The patch prevents this and other similar tools (e.g. KMSAN) from flagging this behavior in the future. Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -102,7 +102,9 @@ static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
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{
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{
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struct nlmsghdr *nlh = nlmsg_hdr(skb);
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struct nlmsghdr *nlh = nlmsg_hdr(skb);
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if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
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if (skb->len < sizeof(nlh->nlmsg_len) ||
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nlh->nlmsg_len < sizeof(*nlh) ||
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skb->len < nlh->nlmsg_len)
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return;
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return;
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if (!netlink_capable(skb, CAP_NET_ADMIN))
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if (!netlink_capable(skb, CAP_NET_ADMIN))
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