Commit b89732c8 authored by Dmitry Vyukov's avatar Dmitry Vyukov Committed by Thomas Gleixner
Browse files

selftests: Fix errno checking in syscall_user_dispatch test 



Successful syscalls don't change errno, so checking errno is wrong
to ensure that a syscall has failed. For example for the following
sequence:

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0xff, 0);
	EXPECT_EQ(EINVAL, errno);
	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, &sel);
	EXPECT_EQ(EINVAL, errno);

only the first syscall may fail and set errno, but the second may succeed
and keep errno intact, and the check will falsely pass.
Or if errno happened to be EINVAL before, even the first check may falsely
pass.

Also use EXPECT/ASSERT consistently. Currently there is an inconsistent mix
without obvious reasons for usage of one or another.

Fixes: 179ef035 ("selftests: Add kselftest for syscall user dispatch")
Signed-off-by: default avatarDmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/af6a04dbfef9af8570f5bab43e3ef1416b62699a.1747839857.git.dvyukov@google.com
parent 19272b37

tools/testing/selftests/syscall_user_dispatch/sud_test.c

+25 −25
Original line number Diff line number Diff line
@@ -79,6 +79,21 @@ TEST_SIGNAL(dispatch_trigger_sigsys, SIGSYS) 
	}

}



static void prctl_valid(struct __test_metadata *_metadata,

			unsigned long op, unsigned long off,

			unsigned long size, void *sel)

{

	EXPECT_EQ(0, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, off, size, sel));

}



static void prctl_invalid(struct __test_metadata *_metadata,

			  unsigned long op, unsigned long off,

			  unsigned long size, void *sel, int err)

{

	EXPECT_EQ(-1, prctl(PR_SET_SYSCALL_USER_DISPATCH, op, off, size, sel));

	EXPECT_EQ(err, errno);

}



TEST(bad_prctl_param)

{

	char sel = SYSCALL_DISPATCH_FILTER_ALLOW;
@@ -86,57 +101,42 @@ TEST(bad_prctl_param) 


	/* Invalid op */

	op = -1;

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0, 0, &sel);

	ASSERT_EQ(EINVAL, errno);

	prctl_invalid(_metadata, op, 0, 0, &sel, EINVAL);



	/* PR_SYS_DISPATCH_OFF */

	op = PR_SYS_DISPATCH_OFF;



	/* offset != 0 */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, 0);

	EXPECT_EQ(EINVAL, errno);

	prctl_invalid(_metadata, op, 0x1, 0x0, 0, EINVAL);



	/* len != 0 */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0xff, 0);

	EXPECT_EQ(EINVAL, errno);

	prctl_invalid(_metadata, op, 0x0, 0xff, 0, EINVAL);



	/* sel != NULL */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, &sel);

	EXPECT_EQ(EINVAL, errno);

	prctl_invalid(_metadata, op, 0x0, 0x0, &sel, EINVAL);



	/* Valid parameter */

	errno = 0;

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x0, 0x0);

	EXPECT_EQ(0, errno);

	prctl_valid(_metadata, op, 0x0, 0x0, 0x0);



	/* PR_SYS_DISPATCH_ON */

	op = PR_SYS_DISPATCH_ON;



	/* Dispatcher region is bad (offset > 0 && len == 0) */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x1, 0x0, &sel);

	EXPECT_EQ(EINVAL, errno);

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, -1L, 0x0, &sel);

	EXPECT_EQ(EINVAL, errno);

	prctl_invalid(_metadata, op, 0x1, 0x0, &sel, EINVAL);

	prctl_invalid(_metadata, op, -1L, 0x0, &sel, EINVAL);



	/* Invalid selector */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, op, 0x0, 0x1, (void *) -1);

	ASSERT_EQ(EFAULT, errno);

	prctl_invalid(_metadata, op, 0x0, 0x1, (void *) -1, EFAULT);



	/*

	 * Dispatcher range overflows unsigned long

	 */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, 1, -1L, &sel);

	ASSERT_EQ(EINVAL, errno) {

		TH_LOG("Should reject bad syscall range");

	}

	prctl_invalid(_metadata, PR_SYS_DISPATCH_ON, 1, -1L, &sel, EINVAL);



	/*

	 * Allowed range overflows usigned long

	 */

	prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, -1L, 0x1, &sel);

	ASSERT_EQ(EINVAL, errno) {

		TH_LOG("Should reject bad syscall range");

	}

	prctl_invalid(_metadata, PR_SYS_DISPATCH_ON, -1L, 0x1, &sel, EINVAL);

}



/*