[PATCH] linux: wait4: Fix incorrect return value comparison

[PATCH] linux: wait4: Fix incorrect return value comparison

[Alistair Francis]

Path 600f00b "linux: Use long time_t for wait4/getrusage" introduced
two bugs:
 - The usage32 struct was set if the wait4 syscall had an error.
 - For 32-bit systems the usage struct was set even if it was specified
   as NULL.

This patch fixes the two issues.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
 sysdeps/unix/sysv/linux/wait4.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/wait4.c b/sysdeps/unix/sysv/linux/wait4.c
index d14bd4da27..796691eb2b 100644
--- a/sysdeps/unix/sysv/linux/wait4.c
+++ b/sysdeps/unix/sysv/linux/wait4.c
@@ -32,10 +32,7 @@ __wait4_time64 (pid_t pid, int *stat_loc, int options, struct __rusage64 *usage)
   struct __rusage32 usage32;
   pid_t ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);
 
-  if (ret != 0)
-    return ret;
-
-  if (usage != NULL)
+  if (ret > 0 && usage != NULL)
     rusage32_to_rusage64 (&usage32, usage);
 
   return ret;
@@ -119,10 +116,8 @@ __wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
 
   ret = __wait4_time64 (pid, stat_loc, options, &usage64);
 
-  if (ret != 0)
-    return ret;
-
-  rusage64_to_rusage (&usage64, usage);
+  if (ret > 0 && usage != NULL)
+    rusage64_to_rusage (&usage64, usage);
 
   return ret;
 }
-- 
2.26.0

Re: [PATCH] linux: wait4: Fix incorrect return value comparison

[Andreas Schwab]

On Apr 06 2020, Alistair Francis via Libc-alpha wrote:

> Path 600f00b "linux: Use long time_t for wait4/getrusage" introduced
> two bugs:
>  - The usage32 struct was set if the wait4 syscall had an error.
>  - For 32-bit systems the usage struct was set even if it was specified
>    as NULL.
>
> This patch fixes the two issues.
>
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  sysdeps/unix/sysv/linux/wait4.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/wait4.c b/sysdeps/unix/sysv/linux/wait4.c
> index d14bd4da27..796691eb2b 100644
> --- a/sysdeps/unix/sysv/linux/wait4.c
> +++ b/sysdeps/unix/sysv/linux/wait4.c
> @@ -32,10 +32,7 @@ __wait4_time64 (pid_t pid, int *stat_loc, int options, struct __rusage64 *usage)
>    struct __rusage32 usage32;
>    pid_t ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options, &usage32);

You should pass NULL if usage is NULL.

> @@ -119,10 +116,8 @@ __wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
>  
>    ret = __wait4_time64 (pid, stat_loc, options, &usage64);

Likewise.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Re: [PATCH] linux: wait4: Fix incorrect return value comparison

[Florian Weimer]

* Alistair Francis via Libc-alpha:

> Path 600f00b "linux: Use long time_t for wait4/getrusage" introduced
> two bugs:
>  - The usage32 struct was set if the wait4 syscall had an error.
>  - For 32-bit systems the usage struct was set even if it was specified
>    as NULL.
>
> This patch fixes the two issues.

Would it make sense to add a test case?