On 5/6/24 11:00 AM, Willem de Bruijn wrote:
John Hubbard wrote:
...
diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c index 353e1e867fbb..0eb61edaad83 100644 --- a/tools/testing/selftests/net/gro.c +++ b/tools/testing/selftests/net/gro.c @@ -110,7 +110,8 @@ static void setup_sock_filter(int fd) const int dport_off = tcp_offset + offsetof(struct tcphdr, dest); const int ethproto_off = offsetof(struct ethhdr, h_proto); int optlen = 0;
- int ipproto_off, opt_ipproto_off;
- int ipproto_off;
- int opt_ipproto_off = 0;
This is only intended to be used in the case where the IP proto is not TCP:
BPF_STMT(BPF_LD + BPF_B + BPF_ABS, ipproto_off),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 2, 0),BPF_STMT(BPF_LD + BPF_B + BPF_ABS, opt_ipproto_off), BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 0, 5),In that case the test tries again at a different offset that accounts for optional IPv6 extension headers.
This is indeed buggy, in that it might accidentally accept packets that should be dropped.
Initializing to 0 compares against against the first byte of the Ethernet header. Which is an external argument to the test. So safest is to initialize opt_ipproto_off to ipproto_off and just repeat the previous check. Perhaps:
@@ -118,6 +118,7 @@ static void setup_sock_filter(int fd) else next_off = offsetof(struct ipv6hdr, nexthdr); ipproto_off = ETH_HLEN + next_off;
opt_ipproto_off = ipproto_off; /* overridden later if may have exthdrs */
OK, thanks for pointing out the right fix, I'll send a v2 that does that.
thanks,