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[PATCH] Fix crash in __longjmp on hppa architecture (BZ #21049)


This fixes a crash in __longjmp on the hppa architecture which happens if the
new sigaltstack is above the current stack. In that case CHECK_SP() does an
INTERNAL_SYSCALL which clobbers %r26. Fix this issue by calling CHECK_SP before
assigning the local register variables r26 and r25.

The bug exists in all glibc versions and is triggered by running the GNU forth
compiler.

I don't have write access, so somebody should commit this for me. Thanks.

ChangeLog:

2017-01-15  Helge Deller  <deller@gmx.de>

	[BZ #21049]
	* sysdeps/hppa/__longjmp.c (__longjmp): Move call to CHECK_SP up
	to avoid clobbering r26.


diff -up ./sysdeps/hppa/__longjmp.c.org ./sysdeps/hppa/__longjmp.c
--- ./sysdeps/hppa/__longjmp.c.org	2017-01-13 10:45:24.180424626 +0100
+++ ./sysdeps/hppa/__longjmp.c	2017-01-13 10:47:41.720409134 +0100
@@ -24,15 +24,16 @@
 void
 __longjmp (__jmp_buf env, int val)
 {
+#ifdef CHECK_SP
+  CHECK_SP (env[0].__jmp_buf.__sp);
+#endif
+
+  {
   /* We must use one of the non-callee saves registers
      for env.  */
   register unsigned long r26 asm ("r26") = (unsigned long)&env[0];
   register unsigned long r25 asm ("r25") = (unsigned long)(val == 0 ? 1 : val);
 
-#ifdef CHECK_SP
-  CHECK_SP (env[0].__jmp_buf.__sp);
-#endif
-
   asm volatile(
 	/* Set return value.  */
 	"copy	%0, %%r28\n\t"
@@ -79,6 +80,8 @@ __longjmp (__jmp_buf env, int val)
 	: /* No outputs.  */
 	: "r" (r25), "r" (r26)
 	: /* No point in clobbers.  */ );
+  }
+
   /* Avoid `volatile function does return' warnings.  */
   for (;;);
 }


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