While compiling filesystem selftests there is a warning:
anon_inode_test.c:45:37: warning: null passed to a callee that
requires a non-null argument [-Wnonnull]
45 | ASSERT_LT(execveat(fd_context, "", NULL, NULL, AT_EMPTY_PATH), 0);
Kernel code is okay to be passed NULL for argv, in which
case it generates argv by itself inside do_execveat_common.
Man page of execvat lists both argv and envp as _Nullable.
But system's unistd.h says different:
extern int execveat (int __fd, const char *__path, char *const __argv[],
char *const __envp[], int __flags)
__THROW __nonnull ((2, 3));
(checked ubuntu 24.04 and fedora 43)
Which is the reason for the compiler warning.
Fix the warning by passing a proper argv array.
Fixes: f8ca403ae77cb ("selftests/filesystems: add exec() test for anonymous
inodes")
Cc: Christian Brauner <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Alejandro Colomar <[email protected]>
Cc: Clint George <[email protected]>
Cc: Ranganath V N <[email protected]>
Signed-off-by: Alexander Atanasov <[email protected]>
---
tools/testing/selftests/filesystems/anon_inode_test.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
Quote from execv's man referenced from execveat's:
On Linux, argv and envp can be specified as NULL.
In both cases, this has the same effect as specifying the argument as a pointer
to a list containing a single null pointer.
***Do not take advantage of this nonstandard and nonportable misfeature!***
Listed as possible to pass NULL, then a big fat warning in the man page
and a header that acctually marks this as invalid usage.
I failed to find the origin of the above contradiction.
It looks like POSIX/GNU/Linux missalignment.
I am putting this here for the record. So may be someone could step in
and make it right.
I've Cc-ed people who made fixes but they are just compile fixes, no
explanation of why the warning exists and in most of them the array is not a
proper
argv.
diff --git a/tools/testing/selftests/filesystems/anon_inode_test.c
b/tools/testing/selftests/filesystems/anon_inode_test.c
index 94c6c81c2301..191549a4304d 100644
--- a/tools/testing/selftests/filesystems/anon_inode_test.c
+++ b/tools/testing/selftests/filesystems/anon_inode_test.c
@@ -4,6 +4,7 @@
#include <fcntl.h>
#include <stdio.h>
+#include <unistd.h>
#include <sys/stat.h>
#include "kselftest_harness.h"
@@ -37,12 +38,13 @@ TEST(anon_inode_no_chmod)
TEST(anon_inode_no_exec)
{
+ char *const argv[] = { "", NULL };
int fd_context;
fd_context = sys_fsopen("tmpfs", 0);
ASSERT_GE(fd_context, 0);
- ASSERT_LT(execveat(fd_context, "", NULL, NULL, AT_EMPTY_PATH), 0);
+ ASSERT_LT(execveat(fd_context, "", argv, NULL, AT_EMPTY_PATH), 0);
ASSERT_EQ(errno, EACCES);
EXPECT_EQ(close(fd_context), 0);
--
2.43.0
