[REVIEW][PATCH 2/3] signal/ia64: Use the force_sig(SIGSEGV,...) in ia64_rt_sigreturn

From: Eric W. Biederman
Date: Mon Sep 24 2018 - 10:22:30 EST

The ia64 handling of failure to return from a signal frame has been trying
to set overlapping fields in struct siginfo since 2.3.43. The si_code
corresponds to the fields that were stomped (not the field that is
actually written), so I can not imagine a piece of userspace code
making sense of the signal frame if it looks closely.

In practice failure to return from a signal frame is a rare event that
almost never happens. Someone using an alternate signal stack to
recover and looking in detail is even more rare. So I presume no one
has ever noticed and reported this ia64 nonsense.

Sort this out by causing ia64 to use force_sig(SIGSEGV) like other architectures.

Fixes: 2.3.43
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: linux-ia64@xxxxxxxxxxxxxxx
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
arch/ia64/kernel/signal.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
index 01fc133b2e4c..9a960829a01d 100644
--- a/arch/ia64/kernel/signal.c
+++ b/arch/ia64/kernel/signal.c
@@ -110,7 +110,6 @@ ia64_rt_sigreturn (struct sigscratch *scr)
extern char ia64_strace_leave_kernel, ia64_leave_kernel;
struct sigcontext __user *sc;
- struct siginfo si;
sigset_t set;
long retval;

@@ -153,14 +152,7 @@ ia64_rt_sigreturn (struct sigscratch *scr)
return retval;

- clear_siginfo(&si);
- 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 = sc;
- force_sig_info(SIGSEGV, &si, current);
+ force_sig(SIGSEGV, current);
return retval;