exec.c: Initialize sa_flags passed to sigaction()

[Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

Posted by Peter Maydell 7 years, 9 months ago

Coverity points out that in the user-only version of cpu_abort() we
call sigaction() with a partially initialized struct sigaction
(CID 1005351). Correct the omission.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 exec.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/exec.c b/exec.c
index ffa1099547..bd8833fc9d 100644
--- a/exec.c
+++ b/exec.c
@@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
         struct sigaction act;
         sigfillset(&act.sa_mask);
         act.sa_handler = SIG_DFL;
+        act.sa_flags = 0;
         sigaction(SIGABRT, &act, NULL);
     }
 #endif
-- 
2.17.0

Re: [Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

Posted by Alex Bennée 7 years, 9 months ago

Peter Maydell <peter.maydell@linaro.org> writes:

> Coverity points out that in the user-only version of cpu_abort() we
> call sigaction() with a partially initialized struct sigaction
> (CID 1005351). Correct the omission.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  exec.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/exec.c b/exec.c
> index ffa1099547..bd8833fc9d 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
>          struct sigaction act;
>          sigfillset(&act.sa_mask);
>          act.sa_handler = SIG_DFL;
> +        act.sa_flags = 0;
>          sigaction(SIGABRT, &act, NULL);
>      }
>  #endif


--
Alex Bennée

Re: [Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

Posted by Philippe Mathieu-Daudé 7 years, 9 months ago

On 05/15/2018 03:27 PM, Peter Maydell wrote:
> Coverity points out that in the user-only version of cpu_abort() we
> call sigaction() with a partially initialized struct sigaction
> (CID 1005351). Correct the omission.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  exec.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/exec.c b/exec.c
> index ffa1099547..bd8833fc9d 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
>          struct sigaction act;

I'd have used the more generic:

           struct sigaction act = { };

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

>          sigfillset(&act.sa_mask);
>          act.sa_handler = SIG_DFL;
> +        act.sa_flags = 0;
>          sigaction(SIGABRT, &act, NULL);
>      }
>  #endif
>

Re: [Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

Posted by Eric Blake 7 years, 9 months ago

On 05/15/2018 03:53 PM, Philippe Mathieu-Daudé wrote:
> On 05/15/2018 03:27 PM, Peter Maydell wrote:
>> Coverity points out that in the user-only version of cpu_abort() we
>> call sigaction() with a partially initialized struct sigaction
>> (CID 1005351). Correct the omission.
>>
>> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
>> ---
>>   exec.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/exec.c b/exec.c
>> index ffa1099547..bd8833fc9d 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
>>           struct sigaction act;
> 
> I'd have used the more generic:
> 
>             struct sigaction act = { };

That's a gcc/clang extension (although we have used it before, 
particularly to shut up buggy versions of clang); better is:

struct sigaction act = { 0 };

if that doesn't trigger the clang bug.

> 
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> 
>>           sigfillset(&act.sa_mask);
>>           act.sa_handler = SIG_DFL;

The sigfillset() has to be done after initialization, but you could also 
use:

struct sigaction act = {
   .sa_handler = SIG_DFL;
};
sigfillset(&act.sa_mask);

as a way to zero-initialize all other fields.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH] exec.c: Initialize sa_flags passed to sigaction()

Posted by Paolo Bonzini 7 years, 9 months ago

On 15/05/2018 20:27, Peter Maydell wrote:
> Coverity points out that in the user-only version of cpu_abort() we
> call sigaction() with a partially initialized struct sigaction
> (CID 1005351). Correct the omission.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  exec.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/exec.c b/exec.c
> index ffa1099547..bd8833fc9d 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1124,6 +1124,7 @@ void cpu_abort(CPUState *cpu, const char *fmt, ...)
>          struct sigaction act;
>          sigfillset(&act.sa_mask);
>          act.sa_handler = SIG_DFL;
> +        act.sa_flags = 0;
>          sigaction(SIGABRT, &act, NULL);
>      }
>  #endif
> 

Queued, thanks.

Paolo