signal/ia64: Use the generic force_sigsegv in setup_frame

The ia64 handling of failure to setup a signal frame has been trying
to set overlapping fields in struct siginfo since 2.3.43.  The si_pid
and si_uid fields are stomped when the si_addr field is set.  The
si_code of SI_KERNEL indicates that si_pid and si_uid should be valid,
and that si_addr does not exist.

Being at odds with the definition of SI_KERNEL and with nothing to
indicate that this was a signal frame setup failure there is no way
for userspace to know that si_addr was filled out instead.

In practice failure to setup a signal frame is rare, and si_pid and
si_uid are always set to 0 when si_code is SI_KERNEL so I expect no
one has looked closely enough before to see this weirdness.  Further
the only difference between force_sigsegv_info and the generic
force_sigsegv other than the return code is that force_sigsegv_info
stomps the si_uid and si_pid fields.

Remove the bug and simplify the code by using force_sigsegv in this
case just like other architectures.

Fixes: 2.3.43
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: linux-ia64@vger.kernel.org
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 12 insertions, 38 deletions

diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
index d1234a5ba4c5..01fc133b2e4c 100644
--- a/arch/ia64/kernel/signal.c
+++ b/arch/ia64/kernel/signal.c
@@ -232,37 +232,6 @@ rbs_on_sig_stack (unsigned long bsp)
 }
 
 static long
-force_sigsegv_info (int sig, void __user *addr)
-{
-        unsigned long flags;
-        struct siginfo si;
-
-        clear_siginfo(&si);
-        if (sig == SIGSEGV) {
-                /*
-                 * Acquiring siglock around the sa_handler-update is almost
-                 * certainly overkill, but this isn't a
-                 * performance-critical path and I'd rather play it safe
-                 * here than having to debug a nasty race if and when
-                 * something changes in kernel/signal.c that would make it
-                 * no longer safe to modify sa_handler without holding the
-                 * lock.
-                 */
-                spin_lock_irqsave(&current->sighand->siglock, flags);
-                current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
-                spin_unlock_irqrestore(&current->sighand->siglock, flags);
-        }
-        si.si_signo = SIGSEGV;
-        si.si_errno = 0;
-        si.si_code = SI_KERNEL;
-        si.si_pid = task_pid_vnr(current);
-        si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
-        si.si_addr = addr;
-        force_sig_info(SIGSEGV, &si, current);
-        return 1;
-}
-
-static long
 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 {
         extern char __kernel_sigtramp[];
@@ -295,15 +264,18 @@ setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
                          * instead so we will die with SIGSEGV.
                          */
                         check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
-                        if (!likely(on_sig_stack(check_sp)))
-                                return force_sigsegv_info(ksig->sig, (void __user *)
-                                                          check_sp);
+                        if (!likely(on_sig_stack(check_sp))) {
+                                force_sigsegv(ksig->sig, current);
+                                return 1;
+                        }
                 }
         }
         frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 
-        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
-                return force_sigsegv_info(ksig->sig, frame);
+        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
+                force_sigsegv(ksig->sig, current);
+                return 1;
+        }
 
         err  = __put_user(ksig->sig, &frame->arg0);
         err |= __put_user(&frame->info, &frame->arg1);
@@ -317,8 +289,10 @@ setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
         err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
         err |= setup_sigcontext(&frame->sc, set, scr);
 
-        if (unlikely(err))
-                return force_sigsegv_info(ksig->sig, frame);
+        if (unlikely(err)) {
+                force_sigsegv(ksig->sig, current);
+                return 1;
+        }
 
         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */