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Handle ss_flags value longjmp safe.

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* exceptions.cc (_cygtls::call_signal_handler): Drop manipulating
	thread's ss_flags here.  It's not safe against longjmp.
	* signal.cc (sigaltstack): Check if we're running on the alternate
	stack and set ss_flags returned in oss to SS_ONSTACK.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2015-06-27 12:08:07 +02:00
parent ba170254e6
commit c2c1b84309
3 changed files with 18 additions and 5 deletions
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7
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,10 @@
2015-06-27 Corinna Vinschen <corinna@vinschen.de>
* exceptions.cc (_cygtls::call_signal_handler): Drop manipulating
thread's ss_flags here. It's not safe against longjmp.
* signal.cc (sigaltstack): Check if we're running on the alternate
stack and set ss_flags returned in oss to SS_ONSTACK.
2015-06-26 Corinna Vinschen <corinna@vinschen.de> 2015-06-26 Corinna Vinschen <corinna@vinschen.de>
* include/cygwin/signal.h: Revert to define MINSIGSTKSZ and SIGSTKSZ * include/cygwin/signal.h: Revert to define MINSIGSTKSZ and SIGSTKSZ

4
winsup/cygwin/exceptions.cc
View File

@ -1599,8 +1599,6 @@ _cygtls::call_signal_handler ()
uintptr_t new_sp = (uintptr_t) _my_tls.altstack.ss_sp uintptr_t new_sp = (uintptr_t) _my_tls.altstack.ss_sp
+ _my_tls.altstack.ss_size; + _my_tls.altstack.ss_size;
new_sp &= ~0xf; new_sp &= ~0xf;
/* Mark alternate stack as used. */
_my_tls.altstack.ss_flags = SS_ONSTACK;
/* In assembler: Save regs on new stack, move to alternate stack, /* In assembler: Save regs on new stack, move to alternate stack,
call thisfunc, revert stack regs. */ call thisfunc, revert stack regs. */
#ifdef __x86_64__ #ifdef __x86_64__
@ -1671,8 +1669,6 @@ _cygtls::call_signal_handler ()
[FUNC] "o" (thisfunc) [FUNC] "o" (thisfunc)
: "memory"); : "memory");
#endif #endif
/* Revert alternate stack to unused. */
_my_tls.altstack.ss_flags = 0;
} }
else else
/* No alternate signal stack requested or available, just call /* No alternate signal stack requested or available, just call

12
winsup/cygwin/signal.cc
View File

@ -667,7 +667,17 @@ sigaltstack (const stack_t *ss, stack_t *oss)
} }
} }
if (oss) if (oss)
memcpy (oss, &me.altstack, sizeof *oss); {
char stack_marker;
memcpy (oss, &me.altstack, sizeof *oss);
if (!me.altstack.ss_flags && me.altstack.ss_sp)
{
if (&stack_marker >= (char *) me.altstack.ss_sp
&& &stack_marker < (char *) me.altstack.ss_sp
+ me.altstack.ss_size)
oss->ss_flags = SS_ONSTACK;
}
}
} }
__except (EFAULT) __except (EFAULT)
{ {