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Save final 'error' in __nptl_setxid_error()

Message ID e56319f8-a4f3-a6d8-9ed7-a6ce492e259b@dektech.com.au
State New, archived
Headers

Commit Message

Peter Zelezny Oct. 13, 2017, 5:16 a.m. UTC 
  On 20/09/17 10:46, Peter Zelezny wrote:

> On 19/09/17 19:43, Florian Weimer wrote:
>
>> On 09/19/2017 09:55 AM, Peter Zelezny wrote:
>>> -      if (olderror != -1)
>>> +      if (olderror != -1) {
>>> +    /* save error to memory so it's not lost in coredumps. */
>>> +    cmdp->error = error;
>>>       /* Mismatch between current and previous results.  */
>>>       abort ();
>>> +    }
>>
>> Would you please change the formatting so that the { } are on lines 
>> by themselves (see the surrounding code for examples)?
>>
>> I think it's better to store the error code in a new local volatile 
>> int variable, so that both old and new error code are accessible.  
>> The old error code seems quite valuable, too.
>>
>> Thanks,
>> Florian
>
> I hope I got the indentation right now, copying nearby code (one tab 
> and two spaces).
>
> Yes, perhaps just saving this to a local stack int would be better, 
> like this?
>
> Cheers,
> -Peter.
>

Any other opinions or concerns on this patch?

Cheers,
-Peter.

Comments

Florian Weimer Oct. 13, 2017, 9:06 p.m. UTC | #1 
* Peter Zelezny:

> Any other opinions or concerns on this patch?

Thanks for the reminder.  I reworded the comment slightly, added a
ChangeLog entry, and pushed it:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=e4f530da0db59ff51549c11ed6ef799b4ade1c87
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Patch

--- glibc.orig/nptl/allocatestack.c	2017-09-19 12:58:11.456588117 +1000
+++ glibc/nptl/allocatestack.c	2017-09-19 12:59:43.906355264 +1000
@@ -1084,8 +1084,12 @@  __nptl_setxid_error (struct xid_command
       if (olderror == error)
 	break;
       if (olderror != -1)
-	/* Mismatch between current and previous results.  */
-	abort ();
+	{
+	  /* save 'error' to memory so it's not lost in coredumps.  */
+	  volatile int xid_err __attribute__((unused)) = error;
+	  /* Mismatch between current and previous results.  */
+	  abort ();
+	}
     }
   while (atomic_compare_and_exchange_bool_acq (&cmdp->error, error, -1));
 }