[PATCH 1/2] selftests/net: suppress clang's "variable-sized type not at the end" warning

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[PATCH v2] selftests/netfilter:...

John Hubbard

5 May 2024 5 May '24

10:26 p.m.

When building with clang, via:

make LLVM=1 -C tools/testing/selftest

...clang warns that "a variable sized type not at the end of a struct or class is a GNU extension".

These cases are not easily changed, because they involve structs that are part of the API. Fortunately, however, the tests seem to be doing just fine (specifically, neither affected test runs any differently with gcc vs. clang builds, on my test system) regardless of the warning. So, all the warning is doing is preventing a clean build of selftests/net.

Fix this by suppressing this particular clang warning for the selftests/net suite.

Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/net/Makefile | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index 7b6918d5f4af..956481174783 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -6,6 +6,10 @@ CFLAGS += -I../../../../usr/include/ $(KHDR_INCLUDES) # Additional include paths needed by kselftest.h CFLAGS += -I../

+ifneq ($(LLVM),) + CFLAGS += -Wno-gnu-variable-sized-type-not-at-end +endif + TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \ rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh

base-commit: f462ae0edd3703edd6f22fe41d336369c38b884b prerequisite-patch-id: b901ece2a5b78503e2fb5480f20e304d36a0ea27

-- 2.45.0

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John Hubbard

5 May 5 May

10:26 p.m.

New subject: [PATCH 2/2] selftests/net: fix uninitialized variables

When building with clang, via:

make LLVM=1 -C tools/testing/selftest

...clang warns about three variables that are not initialized in all cases:

1) The opt_ipproto_off variable is used uninitialized if "testname" is not "ip". This seems like an actual bug.

2) The addr_len is used uninitialized, but only in the assert case, which bails out, so this is harmless.

3) The family variable in add_listener() is only used uninitialized in the error case (neither IPv4 nor IPv6 is specified), so it's also harmless.

Fix by initializing each variable.

Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/net/gro.c | 3 ++- tools/testing/selftests/net/ip_local_port_range.c | 2 +- tools/testing/selftests/net/mptcp/pm_nl_ctl.c | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-)

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; int next_off;

if (proto == PF_INET) diff --git a/tools/testing/selftests/net/ip_local_port_range.c b/tools/testing/selftests/net/ip_local_port_range.c index 193b82745fd8..29451d2244b7 100644 --- a/tools/testing/selftests/net/ip_local_port_range.c +++ b/tools/testing/selftests/net/ip_local_port_range.c @@ -359,7 +359,7 @@ TEST_F(ip_local_port_range, late_bind) struct sockaddr_in v4; struct sockaddr_in6 v6; } addr; - socklen_t addr_len; + socklen_t addr_len = 0; const int one = 1; int fd, err; __u32 range; diff --git a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c index 7426a2cbd4a0..7ad5a59adff2 100644 --- a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c +++ b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c @@ -1276,7 +1276,7 @@ int add_listener(int argc, char *argv[]) struct sockaddr_storage addr; struct sockaddr_in6 *a6; struct sockaddr_in *a4; - u_int16_t family; + u_int16_t family = AF_UNSPEC; int enable = 1; int sock; int err;

-- 2.45.0

Matthieu Baerts

6 May 6 May

7:49 a.m.

New subject: [PATCH 2/2] selftests/net: fix uninitialized variables

Hi John,

On 06/05/2024 00:26, John Hubbard wrote:

...

When building with clang, via:
make LLVM=1 -C tools/testing/selftest
...clang warns about three variables that are not initialized in all cases:

The opt_ipproto_off variable is used uninitialized if "testname" is

not "ip". This seems like an actual bug.

The addr_len is used uninitialized, but only in the assert case, which bails out, so this is harmless.

The family variable in add_listener() is only used uninitialized in the error case (neither IPv4 nor IPv6 is specified), so it's also harmless.

Fix by initializing each variable.

Signed-off-by: John Hubbard jhubbard@nvidia.com

tools/testing/selftests/net/gro.c | 3 ++- tools/testing/selftests/net/ip_local_port_range.c | 2 +- tools/testing/selftests/net/mptcp/pm_nl_ctl.c | 2 +-

Thank you for fixing these warnings!

The modification in the MPTCP selftest directory looks good to me:

Reviewed-by: Matthieu Baerts (NGI0) matttbe@kernel.org

Cheers, Matt

-- Sponsored by the NGI0 Core fund.

Willem de Bruijn

6 p.m.

New subject: [PATCH 2/2] selftests/net: fix uninitialized variables

John Hubbard wrote:

...

When building with clang, via:
make LLVM=1 -C tools/testing/selftest
...clang warns about three variables that are not initialized in all cases:

The opt_ipproto_off variable is used uninitialized if "testname" is

not "ip". This seems like an actual bug.

The addr_len is used uninitialized, but only in the assert case, which bails out, so this is harmless.

The family variable in add_listener() is only used uninitialized in the error case (neither IPv4 nor IPv6 is specified), so it's also harmless.

Fix by initializing each variable.

Signed-off-by: John Hubbard jhubbard@nvidia.com

tools/testing/selftests/net/gro.c | 3 ++- tools/testing/selftests/net/ip_local_port_range.c | 2 +- tools/testing/selftests/net/mptcp/pm_nl_ctl.c | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-)

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 */

John Hubbard

6:50 p.m.

New subject: [PATCH 2/2] selftests/net: fix uninitialized variables

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,

-- John Hubbard NVIDIA

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John Hubbard
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