[PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Thomas Weißschuh]

Newer versions of glibc annotate the poll() function with
__attribute__(access) which triggers a compiler warning inside the
testcase poll_fault.
Avoid this by using a plain NULL which is enough for the testcase.
To avoid potential future warnings also adapt the other EFAULT
testcases, except select_fault as NULL is a valid value for its
argument.

nolibc-test.c: In function ‘run_syscall’:
nolibc-test.c:338:62: warning: ‘poll’ writing 8 bytes into a region of size 0 overflows the destination [-Wstringop-overflow=]
  338 |         do { if (!(cond)) result(llen, SKIPPED); else ret += expect_syserr2(expr, expret, experr1, experr2, llen); } while (0)
      |                                                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nolibc-test.c:341:9: note: in expansion of macro ‘EXPECT_SYSER2’
  341 |         EXPECT_SYSER2(cond, expr, expret, experr, 0)
      |         ^~~~~~~~~~~~~
nolibc-test.c:905:47: note: in expansion of macro ‘EXPECT_SYSER’
  905 |                 CASE_TEST(poll_fault);        EXPECT_SYSER(1, poll((void *)1, 1, 0), -1, EFAULT); break;
      |                                               ^~~~~~~~~~~~
cc1: note: destination object is likely at address zero
In file included from /usr/include/poll.h:1,
                 from nolibc-test.c:33:
/usr/include/sys/poll.h:54:12: note: in a call to function ‘poll’ declared with attribute ‘access (write_only, 1, 2)’
   54 | extern int poll (struct pollfd *__fds, nfds_t __nfds, int __timeout)
      |            ^~~~

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index e2b70641a1e7..a0478f8eaee8 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -895,14 +895,14 @@ int run_syscall(int min, int max)
 		CASE_TEST(lseek_0);           EXPECT_SYSER(1, lseek(0, 0, SEEK_SET), -1, ESPIPE); break;
 		CASE_TEST(mkdir_root);        EXPECT_SYSER(1, mkdir("/", 0755), -1, EEXIST); break;
 		CASE_TEST(mmap_bad);          EXPECT_PTRER(1, mmap(NULL, 0, PROT_READ, MAP_PRIVATE, 0, 0), MAP_FAILED, EINVAL); break;
-		CASE_TEST(munmap_bad);        EXPECT_SYSER(1, munmap((void *)1, 0), -1, EINVAL); break;
+		CASE_TEST(munmap_bad);        EXPECT_SYSER(1, munmap(NULL, 0), -1, EINVAL); break;
 		CASE_TEST(mmap_munmap_good);  EXPECT_SYSZR(1, test_mmap_munmap()); break;
 		CASE_TEST(open_tty);          EXPECT_SYSNE(1, tmp = open("/dev/null", 0), -1); if (tmp != -1) close(tmp); break;
 		CASE_TEST(open_blah);         EXPECT_SYSER(1, tmp = open("/proc/self/blah", 0), -1, ENOENT); if (tmp != -1) close(tmp); break;
 		CASE_TEST(pipe);              EXPECT_SYSZR(1, test_pipe()); break;
 		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
 		CASE_TEST(poll_stdout);       EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
-		CASE_TEST(poll_fault);        EXPECT_SYSER(1, poll((void *)1, 1, 0), -1, EFAULT); break;
+		CASE_TEST(poll_fault);        EXPECT_SYSER(1, poll(NULL, 1, 0), -1, EFAULT); break;
 		CASE_TEST(prctl);             EXPECT_SYSER(1, prctl(PR_SET_NAME, (unsigned long)NULL, 0, 0, 0), -1, EFAULT); break;
 		CASE_TEST(read_badf);         EXPECT_SYSER(1, read(-1, &tmp, 1), -1, EBADF); break;
 		CASE_TEST(rmdir_blah);        EXPECT_SYSER(1, rmdir("/blah"), -1, ENOENT); break;
@@ -911,7 +911,7 @@ int run_syscall(int min, int max)
 		CASE_TEST(select_stdout);     EXPECT_SYSNE(1, ({ fd_set fds; FD_ZERO(&fds); FD_SET(1, &fds); select(2, NULL, &fds, NULL, NULL); }), -1); break;
 		CASE_TEST(select_fault);      EXPECT_SYSER(1, select(1, (void *)1, NULL, NULL, 0), -1, EFAULT); break;
 		CASE_TEST(stat_blah);         EXPECT_SYSER(1, stat("/proc/self/blah", &stat_buf), -1, ENOENT); break;
-		CASE_TEST(stat_fault);        EXPECT_SYSER(1, stat((void *)1, &stat_buf), -1, EFAULT); break;
+		CASE_TEST(stat_fault);        EXPECT_SYSER(1, stat(NULL, &stat_buf), -1, EFAULT); break;
 		CASE_TEST(stat_timestamps);   EXPECT_SYSZR(1, test_stat_timestamps()); break;
 		CASE_TEST(symlink_root);      EXPECT_SYSER(1, symlink("/", "/"), -1, EEXIST); break;
 		CASE_TEST(unlink_root);       EXPECT_SYSER(1, unlink("/"), -1, EISDIR); break;

---
base-commit: f7a6e4791e3d685eddca29b5d16d183ee0407caa
change-id: 20230910-nolibc-poll-fault-4152a6836ef8

Best regards,
-- 
Thomas Weißschuh <linux@weissschuh.net>

Re: [PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Willy Tarreau]

Hi Thomas,

On Sun, Sep 10, 2023 at 09:29:01PM +0200, Thomas Weißschuh wrote:
> Newer versions of glibc annotate the poll() function with
> __attribute__(access) which triggers a compiler warning inside the
> testcase poll_fault.
> Avoid this by using a plain NULL which is enough for the testcase.
> To avoid potential future warnings also adapt the other EFAULT
> testcases, except select_fault as NULL is a valid value for its
> argument.
(...)

Looks good to me. I wouldn't be surprised if we're soon forced to do
the same with select() on some archs where it might be emulated.

Feel free to push it to the shared repo.

Thanks!
Willy

Re: [PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Thomas Weißschuh]

Hi Willy!

On 2023-09-11 08:04:49+0200, Willy Tarreau wrote:
> On Sun, Sep 10, 2023 at 09:29:01PM +0200, Thomas Weißschuh wrote:
> > Newer versions of glibc annotate the poll() function with
> > __attribute__(access) which triggers a compiler warning inside the
> > testcase poll_fault.
> > Avoid this by using a plain NULL which is enough for the testcase.
> > To avoid potential future warnings also adapt the other EFAULT
> > testcases, except select_fault as NULL is a valid value for its
> > argument.
> (...)
> 
> Looks good to me. I wouldn't be surprised if we're soon forced to do
> the same with select() on some archs where it might be emulated.
> 
> Feel free to push it to the shared repo.

Thanks, I pushed it to the "next" branch.

I'd also like to rebase the next branch onto v6.6-rc1, any objections?


Thomas

Re: [PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Willy Tarreau]

On Mon, Sep 11, 2023 at 04:26:41PM +0200, Thomas Weißschuh wrote:
> Hi Willy!
> 
> On 2023-09-11 08:04:49+0200, Willy Tarreau wrote:
> > On Sun, Sep 10, 2023 at 09:29:01PM +0200, Thomas Weißschuh wrote:
> > > Newer versions of glibc annotate the poll() function with
> > > __attribute__(access) which triggers a compiler warning inside the
> > > testcase poll_fault.
> > > Avoid this by using a plain NULL which is enough for the testcase.
> > > To avoid potential future warnings also adapt the other EFAULT
> > > testcases, except select_fault as NULL is a valid value for its
> > > argument.
> > (...)
> > 
> > Looks good to me. I wouldn't be surprised if we're soon forced to do
> > the same with select() on some archs where it might be emulated.
> > 
> > Feel free to push it to the shared repo.
> 
> Thanks, I pushed it to the "next" branch.
> 
> I'd also like to rebase the next branch onto v6.6-rc1, any objections?

Yes, please go on!

Thanks,
Willy

Re: [PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Thomas Weißschuh]

On 2023-09-11 16:30:25+0200, Willy Tarreau wrote:
> On Mon, Sep 11, 2023 at 04:26:41PM +0200, Thomas Weißschuh wrote:
> > On 2023-09-11 08:04:49+0200, Willy Tarreau wrote:
> > > On Sun, Sep 10, 2023 at 09:29:01PM +0200, Thomas Weißschuh wrote:
> > > > Newer versions of glibc annotate the poll() function with
> > > > __attribute__(access) which triggers a compiler warning inside the
> > > > testcase poll_fault.
> > > > Avoid this by using a plain NULL which is enough for the testcase.
> > > > To avoid potential future warnings also adapt the other EFAULT
> > > > testcases, except select_fault as NULL is a valid value for its
> > > > argument.
> > > (...)
> > > 
> > > Looks good to me. I wouldn't be surprised if we're soon forced to do
> > > the same with select() on some archs where it might be emulated.
> > > 
> > > Feel free to push it to the shared repo.
> > 
> > Thanks, I pushed it to the "next" branch.
> > 
> > I'd also like to rebase the next branch onto v6.6-rc1, any objections?
> 
> Yes, please go on!

Done.

I used "git rebase --signoff" and dropped the duplicate signoffs it
generated on my own commits.

It's also pushed to git.kernel.org, could you double-check it?

Thanks,
Thomas

Re: [PATCH] selftests/nolibc: libc-test: avoid -Wstringop-overflow warnings

[Willy Tarreau]

On Mon, Sep 11, 2023 at 04:47:12PM +0200, Thomas Weißschuh wrote:
> I used "git rebase --signoff" and dropped the duplicate signoffs it
> generated on my own commits.
> 
> It's also pushed to git.kernel.org, could you double-check it?

Looks good to me, thank you!

Willy