diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-02-20 13:17:27 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-11 15:14:34 +0200 |
| commit | e9660391d0ebd174b169af3d6de680c2f836027c (patch) | |
| tree | 807efa70f0ff4dfaf303fe5d9d2358d2f93b4a3b /arch | |
| parent | x86/hw_breakpoint: Prevent data breakpoints on cpu_entry_area (diff) | |
| download | linux-e9660391d0ebd174b169af3d6de680c2f836027c.tar.xz linux-e9660391d0ebd174b169af3d6de680c2f836027c.zip | |
x86/doublefault: Remove memmove() call
Use of memmove() in #DF is problematic considered tracing and other
instrumentation.
Remove the memmove() call and simply write out what needs doing; this
even clarifies the code, win-win! The code copies from the espfix64
stack to the normal task stack, there is no possible way for that to
overlap.
Survives selftests/x86, specifically sigreturn_64.
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134058.863038566@linutronix.de
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/traps.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 4cc541051994..48468f61202c 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -299,6 +299,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign regs->ip == (unsigned long)native_irq_return_iret) { struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; + unsigned long *p = (unsigned long *)regs->sp; /* * regs->sp points to the failing IRET frame on the @@ -306,7 +307,11 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign * in gpregs->ss through gpregs->ip. * */ - memmove(&gpregs->ip, (void *)regs->sp, 5*8); + gpregs->ip = p[0]; + gpregs->cs = p[1]; + gpregs->flags = p[2]; + gpregs->sp = p[3]; + gpregs->ss = p[4]; gpregs->orig_ax = 0; /* Missing (lost) #GP error code */ /* |