From dc5dc7e6d71ca9fd1ea01a1418150af3b2937489 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 7 May 2008 18:54:05 -0700 Subject: [PATCH] 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: David S. Miller --- arch/sparc/kernel/signal.c | 20 +++++++++++++++++--- arch/sparc64/kernel/signal.c | 21 +++++++++++++++++---- arch/sparc64/kernel/signal32.c | 18 +++++++++++++++++- 3 files changed, 51 insertions(+), 8 deletions(-) diff --git a/arch/sparc/kernel/signal.c b/arch/sparc/kernel/signal.c index 3c312290c3c2..368157926d24 100644 --- a/arch/sparc/kernel/signal.c +++ b/arch/sparc/kernel/signal.c @@ -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); } diff --git a/arch/sparc64/kernel/signal.c b/arch/sparc64/kernel/signal.c index 45d6bf632daa..07c0443ea3f5 100644 --- a/arch/sparc64/kernel/signal.c +++ b/arch/sparc64/kernel/signal.c @@ -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); } diff --git a/arch/sparc64/kernel/signal32.c b/arch/sparc64/kernel/signal32.c index 9415d2c918c5..0f6b7b156efd 100644 --- a/arch/sparc64/kernel/signal32.c +++ b/arch/sparc64/kernel/signal32.c @@ -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); }