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Fix guard alignment in allocate_stack when stack grows up.

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* nptl/allocatestack.c (allocate_stack): Align old and new guard
	addresses to page boundaries when the stack grows up.
This commit is contained in:
John David Anglin 2017-08-12 14:39:53 -04:00
parent f40b4e86f5
commit d215bbdff3
2 changed files with 11 additions and 2 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2017-08-12 John David Anglin <danglin@gcc.gnu.org>
* nptl/allocatestack.c (allocate_stack): Align old and new guard
addresses to page boundaries when the stack grows up.
* sysdeps/hppa/math-tests.h: New.
[BZ #21016]

10
nptl/allocatestack.c
View File

@ -683,8 +683,14 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
prot) != 0)
goto mprot_error;
#elif _STACK_GROWS_UP
if (mprotect ((char *) pd - pd->guardsize,
pd->guardsize - guardsize, prot) != 0)
char *new_guard = (char *)(((uintptr_t) pd - guardsize)
& ~pagesize_m1);
char *old_guard = (char *)(((uintptr_t) pd - pd->guardsize)
& ~pagesize_m1);
/* The guard size difference might be > 0, but once rounded
to the nearest page the size difference might be zero. */
if (new_guard > old_guard
&& mprotect (old_guard, new_guard - old_guard, prot) != 0)
goto mprot_error;
#endif