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Commit 1e98a0f0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

flow_dissector: fix ipv6 dst, hop-by-hop and routing ext hdrs 



__skb_header_pointer() returns a pointer that must be checked.

Fixes infinite loop reported by Alexei, and add __must_check to
catch these errors earlier.

Fixes: 6a74fcf4 ("flow_dissector: add support for dst, hop-by-hop and routing ext hdrs")
Reported-by: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Tested-by: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarTom Herbert <tom@herbertland.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5b173cf9

include/linux/skbuff.h

+5 −4
Original line number Diff line number Diff line
@@ -2743,7 +2743,8 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, 
__wsum skb_checksum(const struct sk_buff *skb, int offset, int len,

		    __wsum csum);



static inline void *__skb_header_pointer(const struct sk_buff *skb, int offset,

static inline void * __must_check

__skb_header_pointer(const struct sk_buff *skb, int offset,

		     int len, void *data, int hlen, void *buffer)

{

	if (hlen - offset >= len)
@@ -2756,8 +2757,8 @@ static inline void *__skb_header_pointer(const struct sk_buff *skb, int offset, 
	return buffer;

}



static inline void *skb_header_pointer(const struct sk_buff *skb, int offset,

				       int len, void *buffer)

static inline void * __must_check

skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)

{

	return __skb_header_pointer(skb, offset, len, skb->data,

				    skb_headlen(skb), buffer);

net/core/flow_dissector.c

+4 −2
Original line number Diff line number Diff line
@@ -394,9 +394,11 @@ bool __skb_flow_dissect(const struct sk_buff *skb, 


		opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr),

					      data, hlen, &_opthdr);

		if (!opthdr)

			return false;



		ip_proto = _opthdr[0];

		nhoff += (_opthdr[1] + 1) << 3;

		ip_proto = opthdr[0];

		nhoff += (opthdr[1] + 1) << 3;



		goto ip_proto_again;

	}