* [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines
@ 2020-11-30 5:30 Eric Lin
2020-11-30 8:07 ` Pekka Enberg
2020-11-30 8:30 ` Christoph Hellwig
0 siblings, 2 replies; 5+ messages in thread
From: Eric Lin @ 2020-11-30 5:30 UTC (permalink / raw)
To: linux-kernel, linux-riscv, walken, daniel.m.jordan, peterx, akpm,
penberg, aou, palmer, paul.walmsley
Cc: dslin1010, Eric Lin, Alan Kao
In the page fault handler, an access to user-space memory
without get/put_user() or copy_from/to_user() routines is
not resolved properly. Like arm and other architectures,
we need to let it die earlier in page fault handler.
Signed-off-by: Eric Lin <tesheng@andestech.com>
Cc: Alan Kao <alankao@andestech.com>
---
arch/riscv/mm/fault.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 3c8b9e433c67..a452cfa266a2 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -232,6 +232,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
+ if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM)))
+ die(regs, "Accessing user space memory without uaccess routines\n");
+
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (cause == EXC_STORE_PAGE_FAULT)
--
2.17.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines
2020-11-30 5:30 [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines Eric Lin
@ 2020-11-30 8:07 ` Pekka Enberg
2020-12-01 5:32 ` Eric Lin
2020-11-30 8:30 ` Christoph Hellwig
1 sibling, 1 reply; 5+ messages in thread
From: Pekka Enberg @ 2020-11-30 8:07 UTC (permalink / raw)
To: Eric Lin
Cc: LKML, linux-riscv, Michel Lespinasse, Daniel Jordan, Peter Xu,
Andrew Morton, Albert Ou, Palmer Dabbelt, Paul Walmsley,
dslin1010, Alan Kao
On Mon, Nov 30, 2020 at 7:33 AM Eric Lin <tesheng@andestech.com> wrote:
>
> In the page fault handler, an access to user-space memory
> without get/put_user() or copy_from/to_user() routines is
> not resolved properly. Like arm and other architectures,
> we need to let it die earlier in page fault handler.
Fix looks good to me. Can you elaborate on how you found the issue and
how the bug manifests itself?
>
> Signed-off-by: Eric Lin <tesheng@andestech.com>
> Cc: Alan Kao <alankao@andestech.com>
> ---
> arch/riscv/mm/fault.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 3c8b9e433c67..a452cfa266a2 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -232,6 +232,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
> if (user_mode(regs))
> flags |= FAULT_FLAG_USER;
>
> + if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM)))
> + die(regs, "Accessing user space memory without uaccess routines\n");
Let's introduce a die_kernel_fault() helper (similar to arm64, for
example) to ensure same semantics for the different kernel faults. You
can extract the helper from no_context().
> +
> perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
>
> if (cause == EXC_STORE_PAGE_FAULT)
> --
> 2.17.0
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines
2020-11-30 8:07 ` Pekka Enberg
@ 2020-12-01 5:32 ` Eric Lin
0 siblings, 0 replies; 5+ messages in thread
From: Eric Lin @ 2020-12-01 5:32 UTC (permalink / raw)
To: Pekka Enberg
Cc: LKML, linux-riscv, Michel Lespinasse, Daniel Jordan, Peter Xu,
Andrew Morton, Albert Ou, Palmer Dabbelt, Paul Walmsley,
dslin1010@gmail.com, Alan Quey-Liang Kao(?????????)
On Mon, Nov 30, 2020 at 04:07:03PM +0800, Pekka Enberg wrote:
Hi Pekka,
> On Mon, Nov 30, 2020 at 7:33 AM Eric Lin <tesheng@andestech.com> wrote:
> >
> > In the page fault handler, an access to user-space memory
> > without get/put_user() or copy_from/to_user() routines is
> > not resolved properly. Like arm and other architectures,
> > we need to let it die earlier in page fault handler.
>
> Fix looks good to me. Can you elaborate on how you found the issue and
> how the bug manifests itself?
OK, I'll elaborate more on the commit message.
>
> >
> > Signed-off-by: Eric Lin <tesheng@andestech.com>
> > Cc: Alan Kao <alankao@andestech.com>
> > ---
> > arch/riscv/mm/fault.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> > index 3c8b9e433c67..a452cfa266a2 100644
> > --- a/arch/riscv/mm/fault.c
> > +++ b/arch/riscv/mm/fault.c
> > @@ -232,6 +232,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
> > if (user_mode(regs))
> > flags |= FAULT_FLAG_USER;
> >
> > + if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM)))
> > + die(regs, "Accessing user space memory without uaccess routines\n");
>
> Let's introduce a die_kernel_fault() helper (similar to arm64, for
> example) to ensure same semantics for the different kernel faults. You
> can extract the helper from no_context().
OK, I'll add a die_kernel_fault() helper function in v2.
Thanks for your review.
>
> > +
> > perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
> >
> > if (cause == EXC_STORE_PAGE_FAULT)
> > --
> > 2.17.0
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines
2020-11-30 5:30 [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines Eric Lin
2020-11-30 8:07 ` Pekka Enberg
@ 2020-11-30 8:30 ` Christoph Hellwig
2020-12-01 5:20 ` Eric Lin
1 sibling, 1 reply; 5+ messages in thread
From: Christoph Hellwig @ 2020-11-30 8:30 UTC (permalink / raw)
To: Eric Lin
Cc: linux-kernel, linux-riscv, walken, daniel.m.jordan, peterx, akpm,
penberg, aou, palmer, paul.walmsley, dslin1010, Alan Kao
> + if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM)))
Please avoid the overly long line.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines
2020-11-30 8:30 ` Christoph Hellwig
@ 2020-12-01 5:20 ` Eric Lin
0 siblings, 0 replies; 5+ messages in thread
From: Eric Lin @ 2020-12-01 5:20 UTC (permalink / raw)
To: Christoph Hellwig
Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
walken@google.com, daniel.m.jordan@oracle.com, peterx@redhat.com,
akpm@linux-foundation.org, penberg@kernel.org,
aou@eecs.berkeley.edu, palmer@dabbelt.com,
paul.walmsley@sifive.com, dslin1010@gmail.com,
Alan Quey-Liang Kao(?????})
On Mon, Nov 30, 2020 at 04:30:15PM +0800, Christoph Hellwig wrote:
Hi Christoph,
> > + if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status & SR_SUM)))
>
> Please avoid the overly long line.
OK, I'll modify it in v2. Thanks for your review.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-12-01 5:36 UTC | newest]
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2020-11-30 5:30 [PATCH] riscv/mm: Prevent kernel module access user-space memory without uaccess routines Eric Lin
2020-11-30 8:07 ` Pekka Enberg
2020-12-01 5:32 ` Eric Lin
2020-11-30 8:30 ` Christoph Hellwig
2020-12-01 5:20 ` Eric Lin
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