1 files changed, 44 insertions, 15 deletions

diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c
index 7cd1a82dc8c2..33a40f5ef0d2 100644
--- a/arch/um/sys-i386/signal.c
+++ b/arch/um/sys-i386/signal.c
@@ -58,7 +58,7 @@ static int copy_sc_from_user_skas(struct pt_regs *regs,
 }
 
 int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
-                         struct pt_regs *regs)
+                         struct pt_regs *regs, unsigned long sp)
 {
         struct sigcontext sc;
         unsigned long fpregs[HOST_FP_SIZE];
@@ -72,7 +72,7 @@ int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
         sc.edi = REGS_EDI(regs->regs.skas.regs);
         sc.esi = REGS_ESI(regs->regs.skas.regs);
         sc.ebp = REGS_EBP(regs->regs.skas.regs);
-        sc.esp = REGS_SP(regs->regs.skas.regs);
+        sc.esp = sp;
         sc.ebx = REGS_EBX(regs->regs.skas.regs);
         sc.edx = REGS_EDX(regs->regs.skas.regs);
         sc.ecx = REGS_ECX(regs->regs.skas.regs);
@@ -132,7 +132,7 @@ int copy_sc_from_user_tt(struct sigcontext *to, struct sigcontext *from,
 }
 
 int copy_sc_to_user_tt(struct sigcontext *to, struct _fpstate *fp,
-                       struct sigcontext *from, int fpsize)
+                       struct sigcontext *from, int fpsize, unsigned long sp)
 {
         struct _fpstate *to_fp, *from_fp;
         int err;
@@ -140,11 +140,18 @@ int copy_sc_to_user_tt(struct sigcontext *to, struct _fpstate *fp,
         to_fp = (fp ? fp : (struct _fpstate *) (to + 1));
         from_fp = from->fpstate;
         err = copy_to_user(to, from, sizeof(*to));
+
+        /* The SP in the sigcontext is the updated one for the signal
+         * delivery.  The sp passed in is the original, and this needs
+         * to be restored, so we stick it in separately.
+         */
+        err |= copy_to_user(&SC_SP(to), sp, sizeof(sp));
+
         if(from_fp != NULL){
                 err |= copy_to_user(&to->fpstate, &to_fp, sizeof(to->fpstate));
                 err |= copy_to_user(to_fp, from_fp, fpsize);
         }
-        return(err);
+        return err;
 }
 #endif
 
@@ -159,11 +166,11 @@ static int copy_sc_from_user(struct pt_regs *to, void __user *from)
 }
 
 static int copy_sc_to_user(struct sigcontext *to, struct _fpstate *fp,
-                           struct pt_regs *from)
+                           struct pt_regs *from, unsigned long sp)
 {
         return(CHOOSE_MODE(copy_sc_to_user_tt(to, fp, UPT_SC(&from->regs),
-                                              sizeof(*fp)),
-                           copy_sc_to_user_skas(to, fp, from)));
+                                              sizeof(*fp), sp),
+                           copy_sc_to_user_skas(to, fp, from, sp)));
 }
 
 static int copy_ucontext_to_user(struct ucontext *uc, struct _fpstate *fp,
@@ -174,7 +181,7 @@ static int copy_ucontext_to_user(struct ucontext *uc, struct _fpstate *fp,
         err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
         err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
         err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
-        err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs);
+        err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
         return(err);
 }
@@ -207,6 +214,7 @@ int setup_signal_stack_sc(unsigned long stack_top, int sig,
 {
         struct sigframe __user *frame;
         void *restorer;
+        unsigned long save_sp = PT_REGS_SP(regs);
         int err = 0;
 
         stack_top &= -8UL;
@@ -218,9 +226,19 @@ int setup_signal_stack_sc(unsigned long stack_top, int sig,
         if(ka->sa.sa_flags & SA_RESTORER)
                 restorer = ka->sa.sa_restorer;
 
+        /* Update SP now because the page fault handler refuses to extend
+         * the stack if the faulting address is too far below the current
+         * SP, which frame now certainly is.  If there's an error, the original
+         * value is restored on the way out.
+         * When writing the sigcontext to the stack, we have to write the
+         * original value, so that's passed to copy_sc_to_user, which does
+         * the right thing with it.
+         */
+        PT_REGS_SP(regs) = (unsigned long) frame;
+
         err |= __put_user(restorer, &frame->pretcode);
         err |= __put_user(sig, &frame->sig);
-        err |= copy_sc_to_user(&frame->sc, NULL, regs);
+        err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
         err |= __put_user(mask->sig[0], &frame->sc.oldmask);
         if (_NSIG_WORDS > 1)
                 err |= __copy_to_user(&frame->extramask, &mask->sig[1],
@@ -238,7 +256,7 @@ int setup_signal_stack_sc(unsigned long stack_top, int sig,
         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 
         if(err)
-                return(err);
+                goto err;
 
         PT_REGS_SP(regs) = (unsigned long) frame;
         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
@@ -248,7 +266,11 @@ int setup_signal_stack_sc(unsigned long stack_top, int sig,
 
         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
                 ptrace_notify(SIGTRAP);
-        return(0);
+        return 0;
+
+err:
+        PT_REGS_SP(regs) = save_sp;
+        return err;
 }
 
 int setup_signal_stack_si(unsigned long stack_top, int sig,
@@ -257,6 +279,7 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
 {
         struct rt_sigframe __user *frame;
         void *restorer;
+        unsigned long save_sp = PT_REGS_SP(regs);
         int err = 0;
 
         stack_top &= -8UL;
@@ -268,13 +291,16 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
         if(ka->sa.sa_flags & SA_RESTORER)
                 restorer = ka->sa.sa_restorer;
 
+        /* See comment above about why this is here */
+        PT_REGS_SP(regs) = (unsigned long) frame;
+
         err |= __put_user(restorer, &frame->pretcode);
         err |= __put_user(sig, &frame->sig);
         err |= __put_user(&frame->info, &frame->pinfo);
         err |= __put_user(&frame->uc, &frame->puc);
         err |= copy_siginfo_to_user(&frame->info, info);
         err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
-                                     PT_REGS_SP(regs));
+                                     save_sp);
 
         /*
          * This is movl $,%eax ; int $0x80
@@ -288,9 +314,8 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 
         if(err)
-                return(err);
+                goto err;
 
-        PT_REGS_SP(regs) = (unsigned long) frame;
         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
         PT_REGS_EAX(regs) = (unsigned long) sig;
         PT_REGS_EDX(regs) = (unsigned long) &frame->info;
@@ -298,7 +323,11 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
 
         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
                 ptrace_notify(SIGTRAP);
-        return(0);
+        return 0;
+
+err:
+        PT_REGS_SP(regs) = save_sp;
+        return err;
 }
 
 long sys_sigreturn(struct pt_regs regs)