Commit dc5dc7e6 authored by David S. Miller's avatar David S. Miller
Browse files

sparc: Fix SA_ONSTACK signal handling. 



We need to be more liberal about the alignment of the buffer given to
us by sigaltstack().  The user should not need to be mindful of all of
the alignment constraints we have for the stack frame.

This mirrors how we handle this situation in clone() as well.

Also, we align the stack even in non-SA_ONSTACK cases so that signals
due to bad stack alignment can be delivered properly.  This makes such
errors easier to debug and recover from.

Finally, add the sanity check x86 has to make sure we won't overflow
the signal stack.

This fixes glibc testcases nptl/tst-cancel20.c and
nptl/tst-cancelx20.c

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1e38c126

arch/sparc/kernel/signal.c

+17 −3
Original line number Diff line number Diff line
@@ -245,15 +245,29 @@ static inline int invalid_frame_pointer(void __user *fp, int fplen) 


static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)

{

	unsigned long sp;

	unsigned long sp = regs->u_regs[UREG_FP];



	sp = regs->u_regs[UREG_FP];

	/*

	 * If we are on the alternate signal stack and would overflow it, don't.

	 * Return an always-bogus address instead so we will die with SIGSEGV.

	 */

	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))

		return (void __user *) -1L;



	/* This is the X/Open sanctioned signal stack switching.  */

	if (sa->sa_flags & SA_ONSTACK) {

		if (!on_sig_stack(sp) && !((current->sas_ss_sp + current->sas_ss_size) & 7))

		if (sas_ss_flags(sp) == 0)

			sp = current->sas_ss_sp + current->sas_ss_size;

	}



	/* Always align the stack frame.  This handles two cases.  First,

	 * sigaltstack need not be mindful of platform specific stack

	 * alignment.  Second, if we took this signal because the stack

	 * is not aligned properly, we'd like to take the signal cleanly

	 * and report that.

	 */

	sp &= ~7UL;



	return (void __user *)(sp - framesize);

}

arch/sparc64/kernel/signal.c

+17 −4
Original line number Diff line number Diff line
@@ -376,16 +376,29 @@ save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu) 


static inline void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, unsigned long framesize)

{

	unsigned long sp;

	unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS;



	sp = regs->u_regs[UREG_FP] + STACK_BIAS;

	/*

	 * If we are on the alternate signal stack and would overflow it, don't.

	 * Return an always-bogus address instead so we will die with SIGSEGV.

	 */

	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))

		return (void __user *) -1L;



	/* This is the X/Open sanctioned signal stack switching.  */

	if (ka->sa.sa_flags & SA_ONSTACK) {

		if (!on_sig_stack(sp) &&

		    !((current->sas_ss_sp + current->sas_ss_size) & 7))

		if (sas_ss_flags(sp) == 0)

			sp = current->sas_ss_sp + current->sas_ss_size;

	}



	/* Always align the stack frame.  This handles two cases.  First,

	 * sigaltstack need not be mindful of platform specific stack

	 * alignment.  Second, if we took this signal because the stack

	 * is not aligned properly, we'd like to take the signal cleanly

	 * and report that.

	 */

	sp &= ~7UL;



	return (void __user *)(sp - framesize);

}

arch/sparc64/kernel/signal32.c

+17 −1
Original line number Diff line number Diff line
@@ -406,11 +406,27 @@ static void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, uns 
	regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;

	sp = regs->u_regs[UREG_FP];

	

	/*

	 * If we are on the alternate signal stack and would overflow it, don't.

	 * Return an always-bogus address instead so we will die with SIGSEGV.

	 */

	if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))

		return (void __user *) -1L;



	/* This is the X/Open sanctioned signal stack switching.  */

	if (sa->sa_flags & SA_ONSTACK) {

		if (!on_sig_stack(sp) && !((current->sas_ss_sp + current->sas_ss_size) & 7))

		if (sas_ss_flags(sp) == 0)

			sp = current->sas_ss_sp + current->sas_ss_size;

	}



	/* Always align the stack frame.  This handles two cases.  First,

	 * sigaltstack need not be mindful of platform specific stack

	 * alignment.  Second, if we took this signal because the stack

	 * is not aligned properly, we'd like to take the signal cleanly

	 * and report that.

	 */

	sp &= ~7UL;



	return (void __user *)(sp - framesize);

}

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