From a3616a3c02722d1edb95acc7fceade242f6553ba Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 26 Jul 2021 14:23:11 -0500
Subject: [PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
In the fpsp040 code when copyin or copyout fails call
force_sigsegv(SIGSEGV) instead of do_exit(SIGSEGV).
This solves a couple of problems. Because do_exit embeds the ptrace
stop PTRACE_EVENT_EXIT a complete stack frame needs to be present for
that to work correctly. There is always the information needed for a
ptrace stop where get_signal is called. So exiting with a signal
solves the ptrace issue.
Further exiting with a signal ensures that all of the threads in a
process are killed not just the thread that malfunctioned. Which
avoids confusing userspace.
To make force_sigsegv(SIGSEGV) work in fpsp040_die modify the code to
save all of the registers and jump to ret_from_exception (which
ultimately calls get_signal) after fpsp040_die returns.
v2: Updated the branches to use gas's pseudo ops that automatically
calculate the best branch instruction to use for the purpose.
v1: https://lkml.kernel.org/r/87a6m8kgtx.fsf_-_@disp2133
Link: https://lkml.kernel.org/r/87tukghjfs.fsf_-_@disp2133
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
arch/m68k/fpsp040/skeleton.S | 3 ++-
arch/m68k/kernel/traps.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/m68k/fpsp040/skeleton.S b/arch/m68k/fpsp040/skeleton.S
index a8f41615d94a7..439395aa6fb42 100644
--- a/arch/m68k/fpsp040/skeleton.S
+++ b/arch/m68k/fpsp040/skeleton.S
@@ -502,7 +502,8 @@ in_ea:
.section .fixup,#alloc,#execinstr
.even
1:
- jbra fpsp040_die
+ jbsr fpsp040_die
+ jbra .Lnotkern
.section __ex_table,#alloc
.align 4
diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 9e1261462bcc5..5b19fcdcd69e9 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -1150,7 +1150,7 @@ asmlinkage void set_esp0(unsigned long ssp)
*/
asmlinkage void fpsp040_die(void)
{
- do_exit(SIGSEGV);
+ force_sigsegv(SIGSEGV);
}
#ifdef CONFIG_M68KFPU_EMU
--
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