Re: [PATCH] signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
From: Eric W. Biederman <hidden>
Date: 2021-08-25 15:56:36
Also in:
linux-m68k
ebiederm@xmission.com (Eric W. Biederman) writes:
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: Link: https://lkml.kernel.org/r/87a6m8kgtx.fsf_-_@disp2133
Signed-off-by: "Eric W. Biederman" <redacted>Any chance I can get an ack on this patch? Eric
quoted hunk ↗ jump to hunk
--- 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 a8f41615d94a..439395aa6fb4 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 4diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c index 9e1261462bcc..5b19fcdcd69e 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