linux: wait4: Fix incorrect return value comparison

Message ID 20200406183921.530591-1-alistair.francis@wdc.com
State New
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Series
  • linux: wait4: Fix incorrect return value comparison
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Commit Message

H.J. Lu via Libc-alpha April 6, 2020, 6:39 p.m.
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(-)

-- 
2.26.0

Comments

Andreas Schwab April 6, 2020, 7 p.m. | #1
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."
Florian Weimer April 6, 2020, 7:19 p.m. | #2
* 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?

Patch

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;
 }