| From 95bf9d646c3c3f95cb0be7e703b371db8da5be68 Mon Sep 17 00:00:00 2001 |
| From: "Eric W. Biederman" <ebiederm@xmission.com> |
| Date: Wed, 20 Oct 2021 12:43:51 -0500 |
| Subject: signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT |
| |
| From: Eric W. Biederman <ebiederm@xmission.com> |
| |
| commit 95bf9d646c3c3f95cb0be7e703b371db8da5be68 upstream. |
| |
| When an instruction to save or restore a register from the stack fails |
| in _save_fp_context or _restore_fp_context return with -EFAULT. This |
| change was made to r2300_fpu.S[1] but it looks like it got lost with |
| the introduction of EX2[2]. This is also what the other implementation |
| of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and |
| what is needed for the callers to be able to handle the error. |
| |
| Furthermore calling do_exit(SIGSEGV) from bad_stack is wrong because |
| it does not terminate the entire process it just terminates a single |
| thread. |
| |
| As the changed code was the only caller of arch/mips/kernel/syscall.c:bad_stack |
| remove the problematic and now unused helper function. |
| |
| Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> |
| Cc: Maciej Rozycki <macro@orcam.me.uk> |
| Cc: linux-mips@vger.kernel.org |
| [1] 35938a00ba86 ("MIPS: Fix ISA I FP sigcontext access violation handling") |
| [2] f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") |
| Cc: stable@vger.kernel.org |
| Fixes: f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") |
| Acked-by: Maciej W. Rozycki <macro@orcam.me.uk> |
| Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> |
| Link: https://lkml.kernel.org/r/20211020174406.17889-5-ebiederm@xmission.com |
| Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/mips/kernel/r2300_fpu.S | 4 ++-- |
| arch/mips/kernel/syscall.c | 9 --------- |
| 2 files changed, 2 insertions(+), 11 deletions(-) |
| |
| --- a/arch/mips/kernel/r2300_fpu.S |
| +++ b/arch/mips/kernel/r2300_fpu.S |
| @@ -29,8 +29,8 @@ |
| #define EX2(a,b) \ |
| 9: a,##b; \ |
| .section __ex_table,"a"; \ |
| - PTR 9b,bad_stack; \ |
| - PTR 9b+4,bad_stack; \ |
| + PTR 9b,fault; \ |
| + PTR 9b+4,fault; \ |
| .previous |
| |
| .set mips1 |
| --- a/arch/mips/kernel/syscall.c |
| +++ b/arch/mips/kernel/syscall.c |
| @@ -239,12 +239,3 @@ SYSCALL_DEFINE3(cachectl, char *, addr, |
| { |
| return -ENOSYS; |
| } |
| - |
| -/* |
| - * If we ever come here the user sp is bad. Zap the process right away. |
| - * Due to the bad stack signaling wouldn't work. |
| - */ |
| -asmlinkage void bad_stack(void) |
| -{ |
| - do_exit(SIGSEGV); |
| -} |