* [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
@ 2021-09-01 8:45 Alexey Kardashevskiy
2021-09-01 14:59 ` Fabiano Rosas
2021-12-15 0:40 ` Michael Ellerman
0 siblings, 2 replies; 6+ messages in thread
From: Alexey Kardashevskiy @ 2021-09-01 8:45 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Alexey Kardashevskiy, kvm-ppc
The userspace can trigger "vmalloc size %lu allocation failure: exceeds
total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.
This silences the warning by checking the limit before calling vzalloc()
and returns ENOMEM if failed.
This does not call underlying valloc helpers as __vmalloc_node() is only
exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
exported at all.
Spotted by syzkaller.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 474c0cfde384..a59f1cccbcf9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
unsigned long npages = mem->memory_size >> PAGE_SHIFT;
if (change == KVM_MR_CREATE) {
- slot->arch.rmap = vzalloc(array_size(npages,
- sizeof(*slot->arch.rmap)));
+ unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
+
+ if ((cb >> PAGE_SHIFT) > totalram_pages())
+ return -ENOMEM;
+
+ slot->arch.rmap = vzalloc(cb);
if (!slot->arch.rmap)
return -ENOMEM;
}
--
2.30.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
2021-09-01 8:45 [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots Alexey Kardashevskiy
@ 2021-09-01 14:59 ` Fabiano Rosas
2021-09-02 4:25 ` Alexey Kardashevskiy
2021-12-15 0:40 ` Michael Ellerman
1 sibling, 1 reply; 6+ messages in thread
From: Fabiano Rosas @ 2021-09-01 14:59 UTC (permalink / raw)
To: Alexey Kardashevskiy, linuxppc-dev; +Cc: Alexey Kardashevskiy, kvm-ppc
Alexey Kardashevskiy <aik@ozlabs.ru> writes:
> The userspace can trigger "vmalloc size %lu allocation failure: exceeds
> total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.
>
> This silences the warning by checking the limit before calling vzalloc()
> and returns ENOMEM if failed.
>
> This does not call underlying valloc helpers as __vmalloc_node() is only
> exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
> exported at all.
>
> Spotted by syzkaller.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 474c0cfde384..a59f1cccbcf9 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
> unsigned long npages = mem->memory_size >> PAGE_SHIFT;
>
> if (change == KVM_MR_CREATE) {
> - slot->arch.rmap = vzalloc(array_size(npages,
> - sizeof(*slot->arch.rmap)));
> + unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
What does cb mean?
> +
> + if ((cb >> PAGE_SHIFT) > totalram_pages())
> + return -ENOMEM;
> +
> + slot->arch.rmap = vzalloc(cb);
> if (!slot->arch.rmap)
> return -ENOMEM;
> }
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
2021-09-01 14:59 ` Fabiano Rosas
@ 2021-09-02 4:25 ` Alexey Kardashevskiy
2021-09-02 13:08 ` Fabiano Rosas
0 siblings, 1 reply; 6+ messages in thread
From: Alexey Kardashevskiy @ 2021-09-02 4:25 UTC (permalink / raw)
To: Fabiano Rosas, linuxppc-dev; +Cc: kvm-ppc
On 02/09/2021 00:59, Fabiano Rosas wrote:
> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>
>> The userspace can trigger "vmalloc size %lu allocation failure: exceeds
>> total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.
>>
>> This silences the warning by checking the limit before calling vzalloc()
>> and returns ENOMEM if failed.
>>
>> This does not call underlying valloc helpers as __vmalloc_node() is only
>> exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
>> exported at all.
>>
>> Spotted by syzkaller.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> ---
>> arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
>> index 474c0cfde384..a59f1cccbcf9 100644
>> --- a/arch/powerpc/kvm/book3s_hv.c
>> +++ b/arch/powerpc/kvm/book3s_hv.c
>> @@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
>> unsigned long npages = mem->memory_size >> PAGE_SHIFT;
>>
>> if (change == KVM_MR_CREATE) {
>> - slot->arch.rmap = vzalloc(array_size(npages,
>> - sizeof(*slot->arch.rmap)));
>> + unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
>
> What does cb mean?
"count of bytes"
This is from my deep Windows past :)
https://docs.microsoft.com/en-us/windows/win32/stg/coding-style-conventions
>
>> +
>> + if ((cb >> PAGE_SHIFT) > totalram_pages())
>> + return -ENOMEM;
>> +
>> + slot->arch.rmap = vzalloc(cb);
>> if (!slot->arch.rmap)
>> return -ENOMEM;
>> }
--
Alexey
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
2021-09-02 4:25 ` Alexey Kardashevskiy
@ 2021-09-02 13:08 ` Fabiano Rosas
2021-09-02 13:23 ` David Laight
0 siblings, 1 reply; 6+ messages in thread
From: Fabiano Rosas @ 2021-09-02 13:08 UTC (permalink / raw)
To: Alexey Kardashevskiy, linuxppc-dev; +Cc: kvm-ppc
Alexey Kardashevskiy <aik@ozlabs.ru> writes:
> On 02/09/2021 00:59, Fabiano Rosas wrote:
>> Alexey Kardashevskiy <aik@ozlabs.ru> writes:
>>
>>> The userspace can trigger "vmalloc size %lu allocation failure: exceeds
>>> total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.
>>>
>>> This silences the warning by checking the limit before calling vzalloc()
>>> and returns ENOMEM if failed.
>>>
>>> This does not call underlying valloc helpers as __vmalloc_node() is only
>>> exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
>>> exported at all.
>>>
>>> Spotted by syzkaller.
>>>
>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>> ---
>>> arch/powerpc/kvm/book3s_hv.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
>>> index 474c0cfde384..a59f1cccbcf9 100644
>>> --- a/arch/powerpc/kvm/book3s_hv.c
>>> +++ b/arch/powerpc/kvm/book3s_hv.c
>>> @@ -4830,8 +4830,12 @@ static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
>>> unsigned long npages = mem->memory_size >> PAGE_SHIFT;
>>>
>>> if (change == KVM_MR_CREATE) {
>>> - slot->arch.rmap = vzalloc(array_size(npages,
>>> - sizeof(*slot->arch.rmap)));
>>> + unsigned long cb = array_size(npages, sizeof(*slot->arch.rmap));
>>
>> What does cb mean?
>
> "count of bytes"
>
> This is from my deep Windows past :)
>
> https://docs.microsoft.com/en-us/windows/win32/stg/coding-style-conventions
=D How interesting! And according to that link 'sz' means "Zero terminated
String". Imagine the confusion.. haha
>>
>>> +
>>> + if ((cb >> PAGE_SHIFT) > totalram_pages())
>>> + return -ENOMEM;
>>> +
>>> + slot->arch.rmap = vzalloc(cb);
>>> if (!slot->arch.rmap)
>>> return -ENOMEM;
>>> }
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
2021-09-01 8:45 [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots Alexey Kardashevskiy
2021-09-01 14:59 ` Fabiano Rosas
@ 2021-12-15 0:40 ` Michael Ellerman
1 sibling, 0 replies; 6+ messages in thread
From: Michael Ellerman @ 2021-12-15 0:40 UTC (permalink / raw)
To: Alexey Kardashevskiy, linuxppc-dev; +Cc: kvm-ppc
On Wed, 1 Sep 2021 18:45:12 +1000, Alexey Kardashevskiy wrote:
> The userspace can trigger "vmalloc size %lu allocation failure: exceeds
> total pages" via the KVM_SET_USER_MEMORY_REGION ioctl.
>
> This silences the warning by checking the limit before calling vzalloc()
> and returns ENOMEM if failed.
>
> This does not call underlying valloc helpers as __vmalloc_node() is only
> exported when CONFIG_TEST_VMALLOC_MODULE and __vmalloc_node_range() is not
> exported at all.
>
> [...]
Applied to powerpc/next.
[1/1] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots
https://git.kernel.org/powerpc/c/511d25d6b789fffcb20a3eb71899cf974a31bd9d
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-12-15 0:46 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-09-01 8:45 [PATCH kernel] KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots Alexey Kardashevskiy
2021-09-01 14:59 ` Fabiano Rosas
2021-09-02 4:25 ` Alexey Kardashevskiy
2021-09-02 13:08 ` Fabiano Rosas
2021-09-02 13:23 ` David Laight
2021-12-15 0:40 ` Michael Ellerman
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).