From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Christophe LEROY <christophe.leroy@c-s.fr>,
linuxppc-dev@lists.ozlabs.org
Cc: aneesh.kumar@linux.vnet.ibm.com, Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH 12/24] powerpc/mm: Fix reporting of kernel execute faults
Date: Wed, 07 Nov 2018 21:39:44 +1100 [thread overview]
Message-ID: <9dbae86776aefb2aee44cada3ab4cfacb471774b.camel@kernel.crashing.org> (raw)
In-Reply-To: <64d43dc0-60ad-4346-96c9-2ff46867d9c9@c-s.fr>
On Wed, 2018-11-07 at 09:35 +0100, Christophe LEROY wrote:
> Hi Ben,
>
> I have an issue on the 8xx with this change
Ah ouch...
.../...
> > +/* Is this a bad kernel fault ? */
> > +static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
> > + unsigned long address)
> > +{
> > + if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
>
> Do you mind if we had DSISR_PROTFAULT here as well ?
Off the top of my mind, I don't see a problem with that... but it would
definitely require an explanation comment.
> > + printk_ratelimited(KERN_CRIT "kernel tried to execute"
> > + " exec-protected page (%lx) -"
> > + "exploit attempt? (uid: %d)\n",
> > + address, from_kuid(&init_user_ns,
> > + current_uid()));
> > + }
> > + return is_exec || (address >= TASK_SIZE);
> > +}
> > +
> > /*
> > * Define the correct "is_write" bit in error_code based
> > * on the processor family
> > @@ -252,7 +266,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
> > * The kernel should never take an execute fault nor should it
> > * take a page fault to a kernel address.
> > */
> > - if (!is_user && (is_exec || (address >= TASK_SIZE)))
> > + if (unlikely(!is_user && bad_kernel_fault(is_exec, error_code, address)))
> > return SIGSEGV;
> >
> > /* We restore the interrupt state now */
> > @@ -491,11 +505,6 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
> > return 0;
> > }
> >
> > - if (is_exec && (error_code & DSISR_PROTFAULT))
> > - printk_ratelimited(KERN_CRIT "kernel tried to execute NX-protected"
> > - " page (%lx) - exploit attempt? (uid: %d)\n",
> > - address, from_kuid(&init_user_ns, current_uid()));
> > -
> > return SIGSEGV;
> > }
> > NOKPROBE_SYMBOL(__do_page_fault);
> >
next prev parent reply other threads:[~2018-11-07 10:42 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-19 4:49 [PATCH 01/24] powerpc/mm: Move exception_enter/exit to a do_page_fault wrapper Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 02/24] powerpc/mm: Pre-filter SRR1 bits before do_page_fault() Benjamin Herrenschmidt
2017-07-22 16:43 ` LEROY Christophe
2017-07-23 1:10 ` Benjamin Herrenschmidt
2017-07-24 13:48 ` Michael Ellerman
2017-07-19 4:49 ` [PATCH 03/24] powerpc/6xx: Handle DABR match before calling do_page_fault Benjamin Herrenschmidt
2017-08-03 0:19 ` Michael Ellerman
2017-08-03 1:00 ` Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 04/24] powerpc/mm: Update definitions of DSISR bits Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 05/24] powerpc/mm: Update bits used to skip hash_page Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 06/24] powerpc/mm: Use symbolic constants for filtering SRR1 bits on ISIs Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 07/24] powerpc/mm: Move out definition of CPU specific is_write bits Benjamin Herrenschmidt
2017-07-22 16:40 ` LEROY Christophe
2017-07-23 1:06 ` Benjamin Herrenschmidt
2017-07-24 11:58 ` Michael Ellerman
2017-07-19 4:49 ` [PATCH 08/24] powerpc/mm: Move error_code checks for bad faults earlier Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 09/24] powerpc/mm: Overhaul handling of bad page faults Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 10/24] powerpc/mm: Move debugger check to notify_page_fault() Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 11/24] powerpc/mm: Simplify returns from __do_page_fault Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 12/24] powerpc/mm: Fix reporting of kernel execute faults Benjamin Herrenschmidt
2018-11-07 8:35 ` Christophe LEROY
2018-11-07 10:39 ` Benjamin Herrenschmidt [this message]
[not found] ` <87zhtr5d1v.fsf@linux.ibm.com>
2018-11-30 6:08 ` Christophe LEROY
2017-07-19 4:49 ` [PATCH 13/24] powerpc/mm: Make bad_area* helper functions Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 14/24] powerpc/mm: Rework mm_fault_error() Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 15/24] powerpc/mm: Move CMO accounting out of do_page_fault into a helper Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 16/24] powerpc/mm: Cosmetic fix to page fault accounting Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 17/24] powerpc/mm: Move the DSISR_PROTFAULT sanity check Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 18/24] powerpc/mm: Move/simplify faulthandler_disabled() and !mm check Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 19/24] powerpc/mm: Add a bunch of (un)likely annotations to do_page_fault Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 20/24] powerpc/mm: Set fault flags earlier Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 21/24] powerpc/mm: Move page fault VMA access checks to a helper Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 22/24] powerpc/mm: Don't lose "major" fault indication on retry Benjamin Herrenschmidt
2017-07-19 4:49 ` [PATCH 23/24] powerpc/mm: Cleanup check for stack expansion Benjamin Herrenschmidt
2017-07-21 16:59 ` LEROY Christophe
2017-07-24 10:47 ` Michael Ellerman
2017-07-24 17:34 ` LEROY Christophe
2017-07-25 11:19 ` Michael Ellerman
2017-07-31 11:37 ` Christophe LEROY
2017-07-19 4:49 ` [PATCH 24/24] powerpc: Remove old unused icswx based coprocessor support Benjamin Herrenschmidt
2017-08-07 10:41 ` [01/24] powerpc/mm: Move exception_enter/exit to a do_page_fault wrapper Michael Ellerman
2017-08-07 16:37 ` Christophe LEROY
2017-08-08 2:16 ` Michael Ellerman
2017-08-08 6:45 ` Christophe LEROY
2017-08-08 10:00 ` Michael Ellerman
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