diff mbox series

Avoid uninitialized result in sem_open when file does not exist

Message ID 6f9470e3-389d-4cc8-f98f-de9f78ea6e6e@redhat.com
State New
Headers show
Series Avoid uninitialized result in sem_open when file does not exist | expand

Commit Message

Joseph Myers Nov. 8, 2024, 12:29 a.m. UTC
A static analyzer apparently reported an uninitialized use of the
variable result in sem_open in the case where the file is required to
exist but does not exist.

The report appears to be correct; set result to SEM_FAILED in that
case, and add a test for it.

Note: the test passes for me even without the sem_open fix, I guess
because result happens to get value SEM_FAILED (i.e. 0) when
uninitialized.

Tested for x86_64.

Comments

H.J. Lu Nov. 8, 2024, 1:48 a.m. UTC | #1
On Fri, Nov 8, 2024 at 8:30 AM Joseph Myers <josmyers@redhat.com> wrote:
>
> A static analyzer apparently reported an uninitialized use of the
> variable result in sem_open in the case where the file is required to
> exist but does not exist.
>
> The report appears to be correct; set result to SEM_FAILED in that
> case, and add a test for it.
>
> Note: the test passes for me even without the sem_open fix, I guess
> because result happens to get value SEM_FAILED (i.e. 0) when
> uninitialized.
>
> Tested for x86_64.
>
> diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
> index 4c1dc04b20..7f52e7d511 100644
> --- a/sysdeps/pthread/Makefile
> +++ b/sysdeps/pthread/Makefile
> @@ -256,6 +256,7 @@ tests += \
>    tst-sem14 \
>    tst-sem15 \
>    tst-sem16 \
> +  tst-sem17 \
>    tst-setuid3 \
>    tst-signal1 \
>    tst-signal2 \
> diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
> index e41236157a..dab734191a 100644
> --- a/sysdeps/pthread/sem_open.c
> +++ b/sysdeps/pthread/sem_open.c
> @@ -76,6 +76,7 @@ __sem_open (const char *name, int oflag, ...)
>             goto try_create;
>
>           /* Return.  errno is already set.  */
> +         result = SEM_FAILED;
>         }
>        else
>         /* Check whether we already have this semaphore mapped and
> diff --git a/sysdeps/pthread/tst-sem17.c b/sysdeps/pthread/tst-sem17.c
> new file mode 100644
> index 0000000000..c3f05d196f
> --- /dev/null
> +++ b/sysdeps/pthread/tst-sem17.c
> @@ -0,0 +1,35 @@
> +/* Test sem_open with missing file.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <semaphore.h>
> +
> +#include <support/check.h>
> +
> +int
> +do_test (void)
> +{
> +  sem_unlink ("/glibc-tst-sem17");
> +  errno = 0;
> +  sem_t *s = sem_open ("/glibc-tst-sem17", 0);
> +  TEST_VERIFY (s == SEM_FAILED);
> +  TEST_COMPARE (errno, ENOENT);
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
>
> --
> Joseph S. Myers
> josmyers@redhat.com
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.
Adhemerval Zanella Nov. 8, 2024, 8:32 a.m. UTC | #2
On 07/11/24 21:29, Joseph Myers wrote:
> A static analyzer apparently reported an uninitialized use of the
> variable result in sem_open in the case where the file is required to
> exist but does not exist.
> 
> The report appears to be correct; set result to SEM_FAILED in that
> case, and add a test for it.
> 
> Note: the test passes for me even without the sem_open fix, I guess
> because result happens to get value SEM_FAILED (i.e. 0) when
> uninitialized.
> 
> Tested for x86_64.
> 
> diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
> index 4c1dc04b20..7f52e7d511 100644
> --- a/sysdeps/pthread/Makefile
> +++ b/sysdeps/pthread/Makefile
> @@ -256,6 +256,7 @@ tests += \
>    tst-sem14 \
>    tst-sem15 \
>    tst-sem16 \
> +  tst-sem17 \
>    tst-setuid3 \
>    tst-signal1 \
>    tst-signal2 \

We already have a tst-sem17 on nptl, maybe rename it to tst-sem18.

> diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
> index e41236157a..dab734191a 100644
> --- a/sysdeps/pthread/sem_open.c
> +++ b/sysdeps/pthread/sem_open.c
> @@ -76,6 +76,7 @@ __sem_open (const char *name, int oflag, ...)
>  	    goto try_create;
>  
>  	  /* Return.  errno is already set.  */
> +	  result = SEM_FAILED;
>  	}
>        else
>  	/* Check whether we already have this semaphore mapped and
> diff --git a/sysdeps/pthread/tst-sem17.c b/sysdeps/pthread/tst-sem17.c
> new file mode 100644
> index 0000000000..c3f05d196f
> --- /dev/null
> +++ b/sysdeps/pthread/tst-sem17.c
> @@ -0,0 +1,35 @@
> +/* Test sem_open with missing file.
> +   Copyright (C) 2024 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <semaphore.h>
> +
> +#include <support/check.h>
> +
> +int
> +do_test (void)
> +{
> +  sem_unlink ("/glibc-tst-sem17");
> +  errno = 0;
> +  sem_t *s = sem_open ("/glibc-tst-sem17", 0);
> +  TEST_VERIFY (s == SEM_FAILED);
> +  TEST_COMPARE (errno, ENOENT);
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
>
Joseph Myers Nov. 8, 2024, 5:09 p.m. UTC | #3
On Fri, 8 Nov 2024, Adhemerval Zanella Netto wrote:

> We already have a tst-sem17 on nptl, maybe rename it to tst-sem18.

Thanks, I've committed this fix.

Rename new tst-sem17 test to tst-sem18

As noted by Adhemerval, we already have a tst-sem17 in nptl.

Tested for x86_64.

diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
index 7f52e7d511..1a9f2559d9 100644
--- a/sysdeps/pthread/Makefile
+++ b/sysdeps/pthread/Makefile
@@ -256,7 +256,7 @@ tests += \
   tst-sem14 \
   tst-sem15 \
   tst-sem16 \
-  tst-sem17 \
+  tst-sem18 \
   tst-setuid3 \
   tst-signal1 \
   tst-signal2 \
diff --git a/sysdeps/pthread/tst-sem17.c b/sysdeps/pthread/tst-sem18.c
similarity index 92%
rename from sysdeps/pthread/tst-sem17.c
rename to sysdeps/pthread/tst-sem18.c
index c3f05d196f..1be207bcbe 100644
--- a/sysdeps/pthread/tst-sem17.c
+++ b/sysdeps/pthread/tst-sem18.c
@@ -24,9 +24,9 @@
 int
 do_test (void)
 {
-  sem_unlink ("/glibc-tst-sem17");
+  sem_unlink ("/glibc-tst-sem18");
   errno = 0;
-  sem_t *s = sem_open ("/glibc-tst-sem17", 0);
+  sem_t *s = sem_open ("/glibc-tst-sem18", 0);
   TEST_VERIFY (s == SEM_FAILED);
   TEST_COMPARE (errno, ENOENT);
   return 0;
diff mbox series

Patch

diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile
index 4c1dc04b20..7f52e7d511 100644
--- a/sysdeps/pthread/Makefile
+++ b/sysdeps/pthread/Makefile
@@ -256,6 +256,7 @@  tests += \
   tst-sem14 \
   tst-sem15 \
   tst-sem16 \
+  tst-sem17 \
   tst-setuid3 \
   tst-signal1 \
   tst-signal2 \
diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
index e41236157a..dab734191a 100644
--- a/sysdeps/pthread/sem_open.c
+++ b/sysdeps/pthread/sem_open.c
@@ -76,6 +76,7 @@  __sem_open (const char *name, int oflag, ...)
 	    goto try_create;
 
 	  /* Return.  errno is already set.  */
+	  result = SEM_FAILED;
 	}
       else
 	/* Check whether we already have this semaphore mapped and
diff --git a/sysdeps/pthread/tst-sem17.c b/sysdeps/pthread/tst-sem17.c
new file mode 100644
index 0000000000..c3f05d196f
--- /dev/null
+++ b/sysdeps/pthread/tst-sem17.c
@@ -0,0 +1,35 @@ 
+/* Test sem_open with missing file.
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <semaphore.h>
+
+#include <support/check.h>
+
+int
+do_test (void)
+{
+  sem_unlink ("/glibc-tst-sem17");
+  errno = 0;
+  sem_t *s = sem_open ("/glibc-tst-sem17", 0);
+  TEST_VERIFY (s == SEM_FAILED);
+  TEST_COMPARE (errno, ENOENT);
+  return 0;
+}
+
+#include <support/test-driver.c>