From 2d6dbb9a65f4001f2878512078394c11301994f3 Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Thu, 27 Jun 2019 18:12:33 -0700 Subject: [PATCH] selftests/bpf: fix -Wstrict-aliasing in test_sockopt_sk.c MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Let's use union with u8[4] and u32 members for sockopt buffer, that should fix any possible aliasing issues. test_sockopt_sk.c: In function ‘getsetsockopt’: test_sockopt_sk.c:115:2: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] if (*(__u32 *)buf != 0x55AA*2) { ^~ test_sockopt_sk.c:116:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2", ^~~~~~~ Fixes: 8a027dc0d8f5 ("selftests/bpf: add sockopt test that exercises sk helpers") Reported-by: Alexei Starovoitov Signed-off-by: Stanislav Fomichev Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/test_sockopt_sk.c | 51 +++++++++++++-------------- 1 file changed, 24 insertions(+), 27 deletions(-) diff --git a/tools/testing/selftests/bpf/test_sockopt_sk.c b/tools/testing/selftests/bpf/test_sockopt_sk.c index 12e79ed..036b652 100644 --- a/tools/testing/selftests/bpf/test_sockopt_sk.c +++ b/tools/testing/selftests/bpf/test_sockopt_sk.c @@ -22,7 +22,10 @@ static int getsetsockopt(void) { int fd, err; - char buf[4] = {}; + union { + char u8[4]; + __u32 u32; + } buf = {}; socklen_t optlen; fd = socket(AF_INET, SOCK_STREAM, 0); @@ -33,31 +36,31 @@ static int getsetsockopt(void) /* IP_TOS - BPF bypass */ - buf[0] = 0x08; - err = setsockopt(fd, SOL_IP, IP_TOS, buf, 1); + buf.u8[0] = 0x08; + err = setsockopt(fd, SOL_IP, IP_TOS, &buf, 1); if (err) { log_err("Failed to call setsockopt(IP_TOS)"); goto err; } - buf[0] = 0x00; + buf.u8[0] = 0x00; optlen = 1; - err = getsockopt(fd, SOL_IP, IP_TOS, buf, &optlen); + err = getsockopt(fd, SOL_IP, IP_TOS, &buf, &optlen); if (err) { log_err("Failed to call getsockopt(IP_TOS)"); goto err; } - if (buf[0] != 0x08) { + if (buf.u8[0] != 0x08) { log_err("Unexpected getsockopt(IP_TOS) buf[0] 0x%02x != 0x08", - buf[0]); + buf.u8[0]); goto err; } /* IP_TTL - EPERM */ - buf[0] = 1; - err = setsockopt(fd, SOL_IP, IP_TTL, buf, 1); + buf.u8[0] = 1; + err = setsockopt(fd, SOL_IP, IP_TTL, &buf, 1); if (!err || errno != EPERM) { log_err("Unexpected success from setsockopt(IP_TTL)"); goto err; @@ -65,16 +68,16 @@ static int getsetsockopt(void) /* SOL_CUSTOM - handled by BPF */ - buf[0] = 0x01; - err = setsockopt(fd, SOL_CUSTOM, 0, buf, 1); + buf.u8[0] = 0x01; + err = setsockopt(fd, SOL_CUSTOM, 0, &buf, 1); if (err) { log_err("Failed to call setsockopt"); goto err; } - buf[0] = 0x00; + buf.u32 = 0x00; optlen = 4; - err = getsockopt(fd, SOL_CUSTOM, 0, buf, &optlen); + err = getsockopt(fd, SOL_CUSTOM, 0, &buf, &optlen); if (err) { log_err("Failed to call getsockopt"); goto err; @@ -84,37 +87,31 @@ static int getsetsockopt(void) log_err("Unexpected optlen %d != 1", optlen); goto err; } - if (buf[0] != 0x01) { - log_err("Unexpected buf[0] 0x%02x != 0x01", buf[0]); + if (buf.u8[0] != 0x01) { + log_err("Unexpected buf[0] 0x%02x != 0x01", buf.u8[0]); goto err; } /* SO_SNDBUF is overwritten */ - buf[0] = 0x01; - buf[1] = 0x01; - buf[2] = 0x01; - buf[3] = 0x01; - err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, 4); + buf.u32 = 0x01010101; + err = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buf, 4); if (err) { log_err("Failed to call setsockopt(SO_SNDBUF)"); goto err; } - buf[0] = 0x00; - buf[1] = 0x00; - buf[2] = 0x00; - buf[3] = 0x00; + buf.u32 = 0x00; optlen = 4; - err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, buf, &optlen); + err = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buf, &optlen); if (err) { log_err("Failed to call getsockopt(SO_SNDBUF)"); goto err; } - if (*(__u32 *)buf != 0x55AA*2) { + if (buf.u32 != 0x55AA*2) { log_err("Unexpected getsockopt(SO_SNDBUF) 0x%x != 0x55AA*2", - *(__u32 *)buf); + buf.u32); goto err; } -- 2.7.4