* Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process
2021-09-23 9:53 [PATCH] scs: Release kasan vmalloc poison in scs_free process yee.lee
@ 2021-09-23 11:19 ` Kuan-Ying Lee
2021-09-24 14:35 ` Sami Tolvanen
2021-09-24 14:32 ` Sami Tolvanen
2021-09-29 11:54 ` Will Deacon
2 siblings, 1 reply; 6+ messages in thread
From: Kuan-Ying Lee @ 2021-09-23 11:19 UTC (permalink / raw)
To: yee.lee, linux-kernel
Cc: nicholas.Tang, chinwen.chang, Matthias Brugger, Will Deacon,
Sami Tolvanen, moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Thu, 2021-09-23 at 17:53 +0800, yee.lee@mediatek.com wrote:
> From: Yee Lee <yee.lee@mediatek.com>
>
> Since scs allocation has been moved to vmalloc region, the
> shadow stack is protected by kasan_posion_vmalloc.
> However, the vfree_atomic operation needs to access
> its context for scs_free process and causes kasan error
> as the dump info below.
>
> This patch Adds kasan_unpoison_vmalloc() before vfree_atomic,
> which aligns to the prior flow as using kmem_cache.
> The vmalloc region will go back posioned in the following
> vumap() operations.
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4
> Write of size 8 at addr ffff8000100b9000 by task kthreadd/2
>
> CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip)
> Hardware name: linux,dummy-virt (DT)
> Call trace:
> dump_backtrace+0x0/0x43c
> show_stack+0x1c/0x2c
> dump_stack_lvl+0x68/0x84
> print_address_description+0x80/0x394
> kasan_report+0x180/0x1dc
> __asan_report_store8_noabort+0x48/0x58
> llist_add_batch+0x60/0xd4
> vfree_atomic+0x60/0xe0
> scs_free+0x1dc/0x1fc
> scs_release+0xa4/0xd4
> free_task+0x30/0xe4
> __put_task_struct+0x1ec/0x2e0
> delayed_put_task_struct+0x5c/0xa0
> rcu_do_batch+0x62c/0x8a0
> rcu_core+0x60c/0xc14
> rcu_core_si+0x14/0x24
> __do_softirq+0x19c/0x68c
> irq_exit+0x118/0x2dc
> handle_domain_irq+0xcc/0x134
> gic_handle_irq+0x7c/0x1bc
> call_on_irq_stack+0x40/0x70
> do_interrupt_handler+0x78/0x9c
> el1_interrupt+0x34/0x60
> el1h_64_irq_handler+0x1c/0x2c
> el1h_64_irq+0x78/0x7c
> _raw_spin_unlock_irqrestore+0x40/0xcc
> sched_fork+0x4f0/0xb00
> copy_process+0xacc/0x3648
> kernel_clone+0x168/0x534
> kernel_thread+0x13c/0x1b0
> kthreadd+0x2bc/0x400
> ret_from_fork+0x10/0x20
>
> Memory state around the buggy address:
> ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ^
> ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ==================================================================
>
> CC: Matthias Brugger <matthias.bgg@gmail.com>
> CC: Will Deacon <will@kernel.org>
> CC: Sami Tolvanen <samitolvanen@google.com>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> kernel/scs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/scs.c b/kernel/scs.c
> index e2a71fc82fa0..25c0d8e416e6 100644
> --- a/kernel/scs.c
> +++ b/kernel/scs.c
> @@ -68,6 +68,7 @@ void scs_free(void *s)
>
> __scs_account(s, -1);
>
> + kasan_unpoison_vmalloc(s, SCS_SIZE);
> /*
> * We cannot sleep as this can be called in interrupt context,
> * so use this_cpu_cmpxchg to update the cache, and
> vfree_atomic
I'm not sure if we need to add kasan_unpoison_vmalloc() and
kasan_poison_vmalloc() in this file.
As far as I know, vmalloc() and vfree() will do these two functions.
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process
2021-09-23 11:19 ` Kuan-Ying Lee
@ 2021-09-24 14:35 ` Sami Tolvanen
2021-09-29 10:28 ` Kuan-Ying Lee
0 siblings, 1 reply; 6+ messages in thread
From: Sami Tolvanen @ 2021-09-24 14:35 UTC (permalink / raw)
To: Kuan-Ying Lee
Cc: yee.lee, LKML, nicholas.Tang, chinwen.chang, Matthias Brugger,
Will Deacon, moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Thu, Sep 23, 2021 at 4:19 AM Kuan-Ying Lee
<Kuan-Ying.Lee@mediatek.com> wrote:
>
> On Thu, 2021-09-23 at 17:53 +0800, yee.lee@mediatek.com wrote:
> > From: Yee Lee <yee.lee@mediatek.com>
> >
> > Since scs allocation has been moved to vmalloc region, the
> > shadow stack is protected by kasan_posion_vmalloc.
> > However, the vfree_atomic operation needs to access
> > its context for scs_free process and causes kasan error
> > as the dump info below.
> >
> > This patch Adds kasan_unpoison_vmalloc() before vfree_atomic,
> > which aligns to the prior flow as using kmem_cache.
> > The vmalloc region will go back posioned in the following
> > vumap() operations.
> >
> > ==================================================================
> > BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4
> > Write of size 8 at addr ffff8000100b9000 by task kthreadd/2
> >
> > CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip)
> > Hardware name: linux,dummy-virt (DT)
> > Call trace:
> > dump_backtrace+0x0/0x43c
> > show_stack+0x1c/0x2c
> > dump_stack_lvl+0x68/0x84
> > print_address_description+0x80/0x394
> > kasan_report+0x180/0x1dc
> > __asan_report_store8_noabort+0x48/0x58
> > llist_add_batch+0x60/0xd4
> > vfree_atomic+0x60/0xe0
> > scs_free+0x1dc/0x1fc
> > scs_release+0xa4/0xd4
> > free_task+0x30/0xe4
> > __put_task_struct+0x1ec/0x2e0
> > delayed_put_task_struct+0x5c/0xa0
> > rcu_do_batch+0x62c/0x8a0
> > rcu_core+0x60c/0xc14
> > rcu_core_si+0x14/0x24
> > __do_softirq+0x19c/0x68c
> > irq_exit+0x118/0x2dc
> > handle_domain_irq+0xcc/0x134
> > gic_handle_irq+0x7c/0x1bc
> > call_on_irq_stack+0x40/0x70
> > do_interrupt_handler+0x78/0x9c
> > el1_interrupt+0x34/0x60
> > el1h_64_irq_handler+0x1c/0x2c
> > el1h_64_irq+0x78/0x7c
> > _raw_spin_unlock_irqrestore+0x40/0xcc
> > sched_fork+0x4f0/0xb00
> > copy_process+0xacc/0x3648
> > kernel_clone+0x168/0x534
> > kernel_thread+0x13c/0x1b0
> > kthreadd+0x2bc/0x400
> > ret_from_fork+0x10/0x20
> >
> > Memory state around the buggy address:
> > ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ^
> > ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > ==================================================================
> >
> > CC: Matthias Brugger <matthias.bgg@gmail.com>
> > CC: Will Deacon <will@kernel.org>
> > CC: Sami Tolvanen <samitolvanen@google.com>
> > Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> > ---
> > kernel/scs.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/kernel/scs.c b/kernel/scs.c
> > index e2a71fc82fa0..25c0d8e416e6 100644
> > --- a/kernel/scs.c
> > +++ b/kernel/scs.c
> > @@ -68,6 +68,7 @@ void scs_free(void *s)
> >
> > __scs_account(s, -1);
> >
> > + kasan_unpoison_vmalloc(s, SCS_SIZE);
> > /*
> > * We cannot sleep as this can be called in interrupt context,
> > * so use this_cpu_cmpxchg to update the cache, and
> > vfree_atomic
>
> I'm not sure if we need to add kasan_unpoison_vmalloc() and
> kasan_poison_vmalloc() in this file.
>
> As far as I know, vmalloc() and vfree() will do these two functions.
The idea here is to poison the shadow stack after it's set up to catch
unintentional accesses. Outside of compiler instrumentation, nothing
should read or write from this buffer while the task is running.
Sami
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process
2021-09-24 14:35 ` Sami Tolvanen
@ 2021-09-29 10:28 ` Kuan-Ying Lee
0 siblings, 0 replies; 6+ messages in thread
From: Kuan-Ying Lee @ 2021-09-29 10:28 UTC (permalink / raw)
To: Sami Tolvanen
Cc: yee.lee, LKML, nicholas.Tang, chinwen.chang, Matthias Brugger,
Will Deacon, moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support, kuan-ying.lee
On Fri, 2021-09-24 at 07:35 -0700, Sami Tolvanen wrote:
> On Thu, Sep 23, 2021 at 4:19 AM Kuan-Ying Lee
> <Kuan-Ying.Lee@mediatek.com> wrote:
> >
> > On Thu, 2021-09-23 at 17:53 +0800, yee.lee@mediatek.com wrote:
> > > From: Yee Lee <yee.lee@mediatek.com>
> > >
> > > Since scs allocation has been moved to vmalloc region, the
> > > shadow stack is protected by kasan_posion_vmalloc.
> > > However, the vfree_atomic operation needs to access
> > > its context for scs_free process and causes kasan error
> > > as the dump info below.
> > >
> > > This patch Adds kasan_unpoison_vmalloc() before vfree_atomic,
> > > which aligns to the prior flow as using kmem_cache.
> > > The vmalloc region will go back posioned in the following
> > > vumap() operations.
> > >
> > > ================================================================
> > > ==
> > > BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4
> > > Write of size 8 at addr ffff8000100b9000 by task kthreadd/2
> > >
> > > CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip)
> > > Hardware name: linux,dummy-virt (DT)
> > > Call trace:
> > > dump_backtrace+0x0/0x43c
> > > show_stack+0x1c/0x2c
> > > dump_stack_lvl+0x68/0x84
> > > print_address_description+0x80/0x394
> > > kasan_report+0x180/0x1dc
> > > __asan_report_store8_noabort+0x48/0x58
> > > llist_add_batch+0x60/0xd4
> > > vfree_atomic+0x60/0xe0
> > > scs_free+0x1dc/0x1fc
> > > scs_release+0xa4/0xd4
> > > free_task+0x30/0xe4
> > > __put_task_struct+0x1ec/0x2e0
> > > delayed_put_task_struct+0x5c/0xa0
> > > rcu_do_batch+0x62c/0x8a0
> > > rcu_core+0x60c/0xc14
> > > rcu_core_si+0x14/0x24
> > > __do_softirq+0x19c/0x68c
> > > irq_exit+0x118/0x2dc
> > > handle_domain_irq+0xcc/0x134
> > > gic_handle_irq+0x7c/0x1bc
> > > call_on_irq_stack+0x40/0x70
> > > do_interrupt_handler+0x78/0x9c
> > > el1_interrupt+0x34/0x60
> > > el1h_64_irq_handler+0x1c/0x2c
> > > el1h_64_irq+0x78/0x7c
> > > _raw_spin_unlock_irqrestore+0x40/0xcc
> > > sched_fork+0x4f0/0xb00
> > > copy_process+0xacc/0x3648
> > > kernel_clone+0x168/0x534
> > > kernel_thread+0x13c/0x1b0
> > > kthreadd+0x2bc/0x400
> > > ret_from_fork+0x10/0x20
> > >
> > > Memory state around the buggy address:
> > > ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > > f8
> > > ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > > f8
> > > >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > > f8
> > > ^
> > > ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > > f8
> > > ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> > > f8
> > > ================================================================
> > > ==
> > >
> > > CC: Matthias Brugger <matthias.bgg@gmail.com>
> > > CC: Will Deacon <will@kernel.org>
> > > CC: Sami Tolvanen <samitolvanen@google.com>
> > > Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> > > ---
> > > kernel/scs.c | 1 +
> > > 1 file changed, 1 insertion(+)
> > >
> > > diff --git a/kernel/scs.c b/kernel/scs.c
> > > index e2a71fc82fa0..25c0d8e416e6 100644
> > > --- a/kernel/scs.c
> > > +++ b/kernel/scs.c
> > > @@ -68,6 +68,7 @@ void scs_free(void *s)
> > >
> > > __scs_account(s, -1);
> > >
> > > + kasan_unpoison_vmalloc(s, SCS_SIZE);
> > > /*
> > > * We cannot sleep as this can be called in interrupt
> > > context,
> > > * so use this_cpu_cmpxchg to update the cache, and
> > > vfree_atomic
> >
> > I'm not sure if we need to add kasan_unpoison_vmalloc() and
> > kasan_poison_vmalloc() in this file.
> >
> > As far as I know, vmalloc() and vfree() will do these two
> > functions.
>
> The idea here is to poison the shadow stack after it's set up to
> catch
> unintentional accesses. Outside of compiler instrumentation, nothing
> should read or write from this buffer while the task is running.
Got it.
Thanks.
Reviewed-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
>
> Sami
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process
2021-09-23 9:53 [PATCH] scs: Release kasan vmalloc poison in scs_free process yee.lee
2021-09-23 11:19 ` Kuan-Ying Lee
@ 2021-09-24 14:32 ` Sami Tolvanen
2021-09-29 11:54 ` Will Deacon
2 siblings, 0 replies; 6+ messages in thread
From: Sami Tolvanen @ 2021-09-24 14:32 UTC (permalink / raw)
To: yee.lee
Cc: LKML, nicholas.Tang, Kuan-Ying.lee, chinwen.chang,
Matthias Brugger, Will Deacon,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
Hi,
On Thu, Sep 23, 2021 at 2:53 AM <yee.lee@mediatek.com> wrote:
>
> From: Yee Lee <yee.lee@mediatek.com>
>
> Since scs allocation has been moved to vmalloc region, the
> shadow stack is protected by kasan_posion_vmalloc.
> However, the vfree_atomic operation needs to access
> its context for scs_free process and causes kasan error
> as the dump info below.
>
> This patch Adds kasan_unpoison_vmalloc() before vfree_atomic,
> which aligns to the prior flow as using kmem_cache.
> The vmalloc region will go back posioned in the following
> vumap() operations.
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4
> Write of size 8 at addr ffff8000100b9000 by task kthreadd/2
>
> CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip)
> Hardware name: linux,dummy-virt (DT)
> Call trace:
> dump_backtrace+0x0/0x43c
> show_stack+0x1c/0x2c
> dump_stack_lvl+0x68/0x84
> print_address_description+0x80/0x394
> kasan_report+0x180/0x1dc
> __asan_report_store8_noabort+0x48/0x58
> llist_add_batch+0x60/0xd4
> vfree_atomic+0x60/0xe0
> scs_free+0x1dc/0x1fc
> scs_release+0xa4/0xd4
> free_task+0x30/0xe4
> __put_task_struct+0x1ec/0x2e0
> delayed_put_task_struct+0x5c/0xa0
> rcu_do_batch+0x62c/0x8a0
> rcu_core+0x60c/0xc14
> rcu_core_si+0x14/0x24
> __do_softirq+0x19c/0x68c
> irq_exit+0x118/0x2dc
> handle_domain_irq+0xcc/0x134
> gic_handle_irq+0x7c/0x1bc
> call_on_irq_stack+0x40/0x70
> do_interrupt_handler+0x78/0x9c
> el1_interrupt+0x34/0x60
> el1h_64_irq_handler+0x1c/0x2c
> el1h_64_irq+0x78/0x7c
> _raw_spin_unlock_irqrestore+0x40/0xcc
> sched_fork+0x4f0/0xb00
> copy_process+0xacc/0x3648
> kernel_clone+0x168/0x534
> kernel_thread+0x13c/0x1b0
> kthreadd+0x2bc/0x400
> ret_from_fork+0x10/0x20
>
> Memory state around the buggy address:
> ffff8000100b8f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ffff8000100b8f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> >ffff8000100b9000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ^
> ffff8000100b9080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ffff8000100b9100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ==================================================================
>
> CC: Matthias Brugger <matthias.bgg@gmail.com>
> CC: Will Deacon <will@kernel.org>
> CC: Sami Tolvanen <samitolvanen@google.com>
> Signed-off-by: Yee Lee <yee.lee@mediatek.com>
> ---
> kernel/scs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/scs.c b/kernel/scs.c
> index e2a71fc82fa0..25c0d8e416e6 100644
> --- a/kernel/scs.c
> +++ b/kernel/scs.c
> @@ -68,6 +68,7 @@ void scs_free(void *s)
>
> __scs_account(s, -1);
>
> + kasan_unpoison_vmalloc(s, SCS_SIZE);
Thanks for the patch! I believe I had this in the original vmap SCS
series, but Will pointed out that unpoisoning shouldn't be necessary
before vfree_atomic() and I don't remember seeing this KASAN error
back then. I wonder if something changed there? Either way, the patch
looks good to me.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Sami
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] scs: Release kasan vmalloc poison in scs_free process
2021-09-23 9:53 [PATCH] scs: Release kasan vmalloc poison in scs_free process yee.lee
2021-09-23 11:19 ` Kuan-Ying Lee
2021-09-24 14:32 ` Sami Tolvanen
@ 2021-09-29 11:54 ` Will Deacon
2 siblings, 0 replies; 6+ messages in thread
From: Will Deacon @ 2021-09-29 11:54 UTC (permalink / raw)
To: yee.lee
Cc: linux-kernel, nicholas.Tang, Kuan-Ying.lee, chinwen.chang,
Matthias Brugger, Sami Tolvanen,
moderated list:ARM/Mediatek SoC support,
moderated list:ARM/Mediatek SoC support
On Thu, Sep 23, 2021 at 05:53:12PM +0800, yee.lee@mediatek.com wrote:
> From: Yee Lee <yee.lee@mediatek.com>
>
> Since scs allocation has been moved to vmalloc region, the
> shadow stack is protected by kasan_posion_vmalloc.
> However, the vfree_atomic operation needs to access
> its context for scs_free process and causes kasan error
> as the dump info below.
>
> This patch Adds kasan_unpoison_vmalloc() before vfree_atomic,
> which aligns to the prior flow as using kmem_cache.
> The vmalloc region will go back posioned in the following
> vumap() operations.
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in llist_add_batch+0x60/0xd4
> Write of size 8 at addr ffff8000100b9000 by task kthreadd/2
>
> CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.15.0-rc2-11681-(skip)
> Hardware name: linux,dummy-virt (DT)
> Call trace:
> dump_backtrace+0x0/0x43c
> show_stack+0x1c/0x2c
> dump_stack_lvl+0x68/0x84
> print_address_description+0x80/0x394
> kasan_report+0x180/0x1dc
> __asan_report_store8_noabort+0x48/0x58
> llist_add_batch+0x60/0xd4
> vfree_atomic+0x60/0xe0
> scs_free+0x1dc/0x1fc
> scs_release+0xa4/0xd4
> free_task+0x30/0xe4
Thanks, I can reproduce this easily with mainline. We only recently gained
vmalloc support for kasan on arm64, so that's probably why we didn't spot
this earlier.
> diff --git a/kernel/scs.c b/kernel/scs.c
> index e2a71fc82fa0..25c0d8e416e6 100644
> --- a/kernel/scs.c
> +++ b/kernel/scs.c
> @@ -68,6 +68,7 @@ void scs_free(void *s)
>
> __scs_account(s, -1);
>
> + kasan_unpoison_vmalloc(s, SCS_SIZE);
> /*
> * We cannot sleep as this can be called in interrupt context,
> * so use this_cpu_cmpxchg to update the cache, and vfree_atomic
I don't think we should be unpoisoning the stack pages if we're putting
them back on to the local cache -- unpoisoning happens on the alloc path
in that case anyway so that we can zero them.
So how about sending a v2 with this moved a bit later (see below)? With
that change:
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Will Deacon <will@kernel.org>
Thanks,
Will
--->8
diff --git a/kernel/scs.c b/kernel/scs.c
index e2a71fc82fa0..579841be8864 100644
--- a/kernel/scs.c
+++ b/kernel/scs.c
@@ -78,6 +78,7 @@ void scs_free(void *s)
if (this_cpu_cmpxchg(scs_cache[i], 0, s) == NULL)
return;
+ kasan_unpoison_vmalloc(s, SCS_SIZE);
vfree_atomic(s);
}
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