1 files changed, 41 insertions, 15 deletions

diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c
index fe1d065332b1..e75c4e1838b0 100644
--- a/arch/um/sys-x86_64/signal.c
+++ b/arch/um/sys-x86_64/signal.c
@@ -55,7 +55,8 @@ 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, unsigned long mask)
+                         struct pt_regs *regs, unsigned long mask,
+                         unsigned long sp)
 {
         struct faultinfo * fi = &current->thread.arch.faultinfo;
         int err = 0;
@@ -70,7 +71,11 @@ int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
         err |= PUTREG(regs, RDI, to, rdi);
         err |= PUTREG(regs, RSI, to, rsi);
         err |= PUTREG(regs, RBP, to, rbp);
-        err |= PUTREG(regs, RSP, to, rsp);
+        /* Must use orignal RSP, which is passed in, rather than what's in
+         * the pt_regs, because that's already been updated to point at the
+         * signal frame.
+         */
+        err |= __put_user(sp, &to->rsp);
         err |= PUTREG(regs, RBX, to, rbx);
         err |= PUTREG(regs, RDX, to, rdx);
         err |= PUTREG(regs, RCX, to, rcx);
@@ -102,7 +107,7 @@ int copy_sc_to_user_skas(struct sigcontext *to, struct _fpstate *to_fp,
 
 #ifdef CONFIG_MODE_TT
 int copy_sc_from_user_tt(struct sigcontext *to, struct sigcontext *from,
-                        int fpsize)
+                         int fpsize)
 {
         struct _fpstate *to_fp, *from_fp;
         unsigned long sigs;
@@ -120,7 +125,7 @@ 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;
@@ -128,11 +133,17 @@ 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
@@ -148,11 +159,12 @@ 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, unsigned long mask)
+                           struct pt_regs *from, unsigned long mask,
+                           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, mask)));
+                                             sizeof(*fp), sp),
+                          copy_sc_to_user_skas(to, fp, from, mask, sp)));
 }
 
 struct rt_sigframe
@@ -170,6 +182,7 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
 {
         struct rt_sigframe __user *frame;
         struct _fpstate __user *fp = NULL;
+        unsigned long save_sp = PT_REGS_RSP(regs);
         int err = 0;
         struct task_struct *me = current;
 
@@ -193,14 +206,25 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
                         goto out;
         }
 
+        /* 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_RSP(regs) = (unsigned long) frame;
+
         /* Create the ucontext.  */
         err |= __put_user(0, &frame->uc.uc_flags);
         err |= __put_user(0, &frame->uc.uc_link);
         err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
-        err |= __put_user(sas_ss_flags(PT_REGS_SP(regs)),
+        err |= __put_user(sas_ss_flags(save_sp),
                           &frame->uc.uc_stack.ss_flags);
         err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
-        err |= copy_sc_to_user(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
+        err |= copy_sc_to_user(&frame->uc.uc_mcontext, fp, regs, set->sig[0],
+                save_sp);
         err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
         if (sizeof(*set) == 16) {
                 __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
@@ -217,10 +241,10 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
                 err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
         else
                 /* could use a vstub here */
-                goto out;
+                goto restore_sp;
 
         if (err)
-                goto out;
+                goto restore_sp;
 
         /* Set up registers for signal handler */
         {
@@ -238,10 +262,12 @@ int setup_signal_stack_si(unsigned long stack_top, int sig,
         PT_REGS_RSI(regs) = (unsigned long) &frame->info;
         PT_REGS_RDX(regs) = (unsigned long) &frame->uc;
         PT_REGS_RIP(regs) = (unsigned long) ka->sa.sa_handler;
-
-        PT_REGS_RSP(regs) = (unsigned long) frame;
  out:
-        return(err);
+        return err;
+
+restore_sp:
+        PT_REGS_RSP(regs) = save_sp;
+        return err;
 }
 
 long sys_rt_sigreturn(struct pt_regs *regs)