Fix -Wunused-result warning generated when compiled with gcc 13.3.0,
by checking fread's return value and handling errors, preventing
potential failures when reading from stdin.

Fixes compiler warning:
warning: ignoring return value of 'fread' declared with attribute
'warn_unused_result' [-Wunused-result]

Fixes: 806a15b2545e ("kselftests/arm64: add PAuth test for whether exec() changes keys")

Signed-off-by: Bala-Vignesh-Reddy <reddybalavignesh9979@gmail.com>
---
Changes in v2:
	Use EXIT_FAILURE instead of -1.
---
 tools/testing/selftests/arm64/pauth/exec_target.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/pauth/exec_target.c b/tools/testing/selftests/arm64/pauth/exec_target.c
index 4435600ca400..e597861b26d6 100644
--- a/tools/testing/selftests/arm64/pauth/exec_target.c
+++ b/tools/testing/selftests/arm64/pauth/exec_target.c
@@ -13,7 +13,12 @@ int main(void)
 	unsigned long hwcaps;
 	size_t val;
 
-	fread(&val, sizeof(size_t), 1, stdin);
+	size_t size = fread(&val, sizeof(size_t), 1, stdin);
+
+	if (size != 1) {
+		fprintf(stderr, "Could not read input from stdin\n");
+		return EXIT_FAILURE;
+	}
 
 	/* don't try to execute illegal (unimplemented) instructions) caller
 	 * should have checked this and keep worker simple
-- 
2.43.0

On Fri, 08 Aug 2025 13:38:30 +0530, Bala-Vignesh-Reddy wrote:
> Fix -Wunused-result warning generated when compiled with gcc 13.3.0,
> by checking fread's return value and handling errors, preventing
> potential failures when reading from stdin.
> 
> Fixes compiler warning:
> warning: ignoring return value of 'fread' declared with attribute
> 'warn_unused_result' [-Wunused-result]
> 
> [...]

Applied to arm64 (for-next/selftests), thanks!

[1/1] selftests: arm64: Check fread return value in exec_target
      https://git.kernel.org/arm64/c/a679e5683d3e

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev

On Fri, Aug 08, 2025 at 01:38:30PM +0530, Bala-Vignesh-Reddy wrote:
> Fix -Wunused-result warning generated when compiled with gcc 13.3.0,
> by checking fread's return value and handling errors, preventing
> potential failures when reading from stdin.
> 
> Fixes compiler warning:
> warning: ignoring return value of 'fread' declared with attribute
> 'warn_unused_result' [-Wunused-result]

Reviewed-by: Mark Brown <broonie@kernel.org>