From: "Eric W. Biederman" ebiederm@xmission.com
[ Upstream commit a3616a3c02722d1edb95acc7fceade242f6553ba ]
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 Signed-off-by: Finn Thain fthain@linux-m68k.org --- 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 31a9c634c81e..081922c72daa 100644 --- a/arch/m68k/fpsp040/skeleton.S +++ b/arch/m68k/fpsp040/skeleton.S @@ -502,7 +502,8 @@ in_ea: .section .fixup,"ax" .even 1: - jbra fpsp040_die + jbsr fpsp040_die + jbra .Lnotkern
.section __ex_table,"a" .align 4 diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c index 35f706d836c5..c6f18dc5884b 100644 --- a/arch/m68k/kernel/traps.c +++ b/arch/m68k/kernel/traps.c @@ -1155,7 +1155,7 @@ asmlinkage void set_esp0(unsigned long ssp) */ asmlinkage void fpsp040_die(void) { - do_exit(SIGSEGV); + force_sigsegv(SIGSEGV); }
#ifdef CONFIG_M68KFPU_EMU
[ Sasha's backport helper bot ]
Hi,
The upstream commit SHA1 provided is correct: a3616a3c02722d1edb95acc7fceade242f6553ba
WARNING: Author mismatch between patch and upstream commit: Backport author: Finn Thainfthain@linux-m68k.org Commit author: Eric W. Biedermanebiederm@xmission.com
Status in newer kernel trees: 6.12.y | Present (exact SHA1) 6.6.y | Present (exact SHA1) 6.1.y | Present (exact SHA1) 5.15.y | Present (exact SHA1) 5.10.y | Not found 5.4.y | Not found
Note: The patch differs from the upstream commit: --- 1: a3616a3c02722 ! 1: bf9f85b11138f signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die @@ Metadata ## Commit message ## signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die
+ [ Upstream commit a3616a3c02722d1edb95acc7fceade242f6553ba ] + In the fpsp040 code when copyin or copyout fails call force_sigsegv(SIGSEGV) instead of do_exit(SIGSEGV).
@@ Commit message 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 + Signed-off-by: Finn Thain fthain@linux-m68k.org
## arch/m68k/fpsp040/skeleton.S ## @@ arch/m68k/fpsp040/skeleton.S: in_ea: - .section .fixup,#alloc,#execinstr + .section .fixup,"ax" .even 1: - jbra fpsp040_die + jbsr fpsp040_die + jbra .Lnotkern
- .section __ex_table,#alloc + .section __ex_table,"a" .align 4
## arch/m68k/kernel/traps.c ## ---
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-5.4.y | Success | Success |
linux-stable-mirror@lists.linaro.org
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Finn Thain -
Sasha Levin