[PATCH v1] selftests/landlock: Fix readlink check

[Mickaël Salaün]

The audit_init_filter_exe() helper incorrectly checks the readlink(2)
error because an unsigned integer is used to store the result.  Use a
signed integer for this check.

Cc: Günther Noack <gnoack at google.com>
Reported-by: Dan Carpenter <dan.carpenter at linaro.org>
Closes: https://lore.kernel.org/r/aDbFwyZ_fM-IO7sC@stanley.mountain
Fixes: 6a500b22971c ("selftests/landlock: Add tests for audit flags and domain IDs")
---
 tools/testing/selftests/landlock/audit.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/landlock/audit.h b/tools/testing/selftests/landlock/audit.h
index 18a6014920b5..b16986aa6442 100644
--- a/tools/testing/selftests/landlock/audit.h
+++ b/tools/testing/selftests/landlock/audit.h
@@ -403,11 +403,12 @@ static int audit_init_filter_exe(struct audit_filter *filter, const char *path)
 	/* It is assume that there is not already filtering rules. */
 	filter->record_type = AUDIT_EXE;
 	if (!path) {
-		filter->exe_len = readlink("/proc/self/exe", filter->exe,
-					   sizeof(filter->exe) - 1);
-		if (filter->exe_len < 0)
+		int ret = readlink("/proc/self/exe", filter->exe,
+				   sizeof(filter->exe) - 1);
+		if (ret < 0)
 			return -errno;
 
+		filter->exe_len = ret;
 		return 0;
 	}
 
-- 
2.49.0