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* [PATCH seccomp] selftests/seccomp: Fix compile warning when CC=clang
@ 2022-05-26 22:34 YiFei Zhu
  2022-05-27 20:34 ` Kees Cook
  0 siblings, 1 reply; 2+ messages in thread
From: YiFei Zhu @ 2022-05-26 22:34 UTC (permalink / raw)
  To: Kees Cook
  Cc: Andy Lutomirski, Will Drewry, Shuah Khan, Christian Brauner,
	linux-kselftest, bpf, llvm, YiFei Zhu

clang has -Wconstant-conversion by default, and the constant 0xAAAAAAAAA
(9 As) being converted to an int, which is generally 32 bits, results
in the compile warning:

  clang -Wl,-no-as-needed -Wall -isystem ../../../../usr/include/  -lpthread  seccomp_bpf.c -lcap -o seccomp_bpf
  seccomp_bpf.c:812:67: warning: implicit conversion from 'long' to 'int' changes value from 45812984490 to -1431655766 [-Wconstant-conversion]
          int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
              ~~~~                                                         ^~~~~~~~~~~
  1 warning generated.

-1431655766 is the expected truncation, 0xAAAAAAAA (8 As), so use
this directly in the code to avoid the warning.

Fixes: 3932fcecd962 ("selftests/seccomp: Add test for unknown SECCOMP_RET kill behavior")
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 136df5b76319..4ae6c8991307 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -809,7 +809,7 @@ void kill_thread_or_group(struct __test_metadata *_metadata,
 		.len = (unsigned short)ARRAY_SIZE(filter_thread),
 		.filter = filter_thread,
 	};
-	int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
+	int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAA;
 	struct sock_filter filter_process[] = {
 		BPF_STMT(BPF_LD|BPF_W|BPF_ABS,
 			offsetof(struct seccomp_data, nr)),
-- 
2.36.1.124.g0e6072fb45-goog


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH seccomp] selftests/seccomp: Fix compile warning when CC=clang
  2022-05-26 22:34 [PATCH seccomp] selftests/seccomp: Fix compile warning when CC=clang YiFei Zhu
@ 2022-05-27 20:34 ` Kees Cook
  0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2022-05-27 20:34 UTC (permalink / raw)
  To: zhuyifei; +Cc: Kees Cook, shuah, luto, wad, bpf, brauner, llvm, linux-kselftest

On Thu, 26 May 2022 22:34:07 +0000, YiFei Zhu wrote:
> clang has -Wconstant-conversion by default, and the constant 0xAAAAAAAAA
> (9 As) being converted to an int, which is generally 32 bits, results
> in the compile warning:
> 
>   clang -Wl,-no-as-needed -Wall -isystem ../../../../usr/include/  -lpthread  seccomp_bpf.c -lcap -o seccomp_bpf
>   seccomp_bpf.c:812:67: warning: implicit conversion from 'long' to 'int' changes value from 45812984490 to -1431655766 [-Wconstant-conversion]
>           int kill = kill_how == KILL_PROCESS ? SECCOMP_RET_KILL_PROCESS : 0xAAAAAAAAA;
>               ~~~~                                                         ^~~~~~~~~~~
>   1 warning generated.
> 
> [...]

Applied to for-next/seccomp, thanks!

[1/1] selftests/seccomp: Fix compile warning when CC=clang
      https://git.kernel.org/kees/c/73a8dbafd31a

-- 
Kees Cook


^ permalink raw reply	[flat|nested] 2+ messages in thread

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2022-05-26 22:34 [PATCH seccomp] selftests/seccomp: Fix compile warning when CC=clang YiFei Zhu
2022-05-27 20:34 ` Kees Cook

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