[PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[Rustam Kovhaev]

Make use of the struct_size() helper to avoid any potential type
mistakes and protect against potential integer overflows
Make use of the flex_array_size() helper to calculate the size of a
flexible array member within an enclosing structure

Cc: stable@vger.kernel.org
Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
---
 virt/kvm/kvm_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index cf88233b819a..68edd25dcb11 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4350,10 +4350,10 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
 	new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1),
 			  GFP_KERNEL_ACCOUNT);
 	if (new_bus) {
-		memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range));
+		memcpy(new_bus, bus, struct_size(bus, range, i));
 		new_bus->dev_count--;
 		memcpy(new_bus->range + i, bus->range + i + 1,
-		       (new_bus->dev_count - i) * sizeof(struct kvm_io_range));
+				flex_array_size(new_bus, range, new_bus->dev_count - i));
 	} else {
 		pr_err("kvm: failed to shrink bus, removing it completely\n");
 		for (j = 0; j < bus->dev_count; j++) {
-- 
2.28.0

Re: [PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[Gustavo A. R. Silva]

On Fri, Sep 18, 2020 at 05:05:00AM -0700, Rustam Kovhaev wrote:
> Make use of the struct_size() helper to avoid any potential type
> mistakes and protect against potential integer overflows
> Make use of the flex_array_size() helper to calculate the size of a
> flexible array member within an enclosing structure
> 
> Cc: stable@vger.kernel.org

I don't think this change applies for -stable.

> Suggested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
--
Gustavo

> ---
>  virt/kvm/kvm_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index cf88233b819a..68edd25dcb11 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4350,10 +4350,10 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
>  	new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1),
>  			  GFP_KERNEL_ACCOUNT);
>  	if (new_bus) {
> -		memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range));
> +		memcpy(new_bus, bus, struct_size(bus, range, i));
>  		new_bus->dev_count--;
>  		memcpy(new_bus->range + i, bus->range + i + 1,
> -		       (new_bus->dev_count - i) * sizeof(struct kvm_io_range));
> +				flex_array_size(new_bus, range, new_bus->dev_count - i));
>  	} else {
>  		pr_err("kvm: failed to shrink bus, removing it completely\n");
>  		for (j = 0; j < bus->dev_count; j++) {
> -- 
> 2.28.0
> 

Re: [PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[Sasha Levin]

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Hi

[This is an automated email]

This commit has been processed because it contains a -stable tag.
The stable tag indicates that it's relevant for the following trees: all

The bot has tested the following trees: v5.8.10, v5.4.66, v4.19.146, v4.14.198, v4.9.236, v4.4.236.

v5.8.10: Build OK!
v5.4.66: Build failed! Errors:
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function 'flex_array_size'; did you mean 'array_size'? [-Werror=implicit-function-declaration]
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:30: error: 'range' undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function 'flex_array_size'; did you mean 'array_size'? [-Werror=implicit-function-declaration]
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:30: error: 'range' undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function 'flex_array_size'; did you mean 'array_size'? [-Werror=implicit-function-declaration]
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:30: error: 'range' undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function ‘flex_array_size’; did you mean ‘array_size’? [-Werror=implicit-function-declaration]
    virt/kvm/kvm_main.c:4034:30: error: ‘range’ undeclared (first use in this function)
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function 'flex_array_size'; did you mean 'array_size'? [-Werror=implicit-function-declaration]
    arch/s390/kvm/../../../virt/kvm/kvm_main.c:4034:30: error: 'range' undeclared (first use in this function)
    arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4034:5: error: implicit declaration of function 'flex_array_size'; did you mean 'array_size'? [-Werror=implicit-function-declaration]
    arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4034:30: error: 'range' undeclared (first use in this function)

v4.19.146: Failed to apply! Possible dependencies:
    0804c849f1df ("kvm/x86 : add coalesced pio support")
    360cae313702 ("KVM: PPC: Book3S HV: Nested guest entry via hypercall")
    41f4e631daf8 ("KVM: PPC: Book3S HV: Extract PMU save/restore operations as C-callable functions")
    89329c0be8bd ("KVM: PPC: Book3S HV: Clear partition table entry on vm teardown")
    8e3f5fc1045d ("KVM: PPC: Book3S HV: Framework and hcall stubs for nested virtualization")
    90952cd38859 ("kvm: Use struct_size() in kmalloc()")
    95a6432ce903 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests")
    9943450b7b88 ("kvm/x86 : add document for coalesced mmio")
    aa069a996951 ("KVM: PPC: Book3S HV: Add a VM capability to enable nested virtualization")
    b12ce36a43f2 ("kvm: Add memcg accounting to KVM allocations")
    df709a296ef7 ("KVM: PPC: Book3S HV: Simplify real-mode interrupt handling")
    f7035ce9f1df ("KVM: PPC: Book3S HV: Move interrupt delivery on guest entry to C code")

v4.14.198: Failed to apply! Possible dependencies:
    0804c849f1df ("kvm/x86 : add coalesced pio support")
    7bf14c28ee77 ("Merge branch 'x86/hyperv' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
    90952cd38859 ("kvm: Use struct_size() in kmalloc()")
    b12ce36a43f2 ("kvm: Add memcg accounting to KVM allocations")
    d4c67a7a54f1 ("kvm: use insert sort in kvm_io_bus_register_dev function")

v4.9.236: Failed to apply! Possible dependencies:
    0804c849f1df ("kvm/x86 : add coalesced pio support")
    4a12f9517728 ("KVM: mark kvm->busses as rcu protected")
    7bf14c28ee77 ("Merge branch 'x86/hyperv' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")
    90952cd38859 ("kvm: Use struct_size() in kmalloc()")
    b12ce36a43f2 ("kvm: Add memcg accounting to KVM allocations")
    d4c67a7a54f1 ("kvm: use insert sort in kvm_io_bus_register_dev function")

v4.4.236: Failed to apply! Possible dependencies:
    4a12f9517728 ("KVM: mark kvm->busses as rcu protected")
    5c919412fe61 ("kvm/x86: Hyper-V synthetic interrupt controller")
    6308630bd3db ("kvm/x86: split ioapic-handled and EOI exit bitmaps")
    765eaa0f70ea ("kvm/x86: Hyper-V SynIC message slot pending clearing at SINT ack")
    90952cd38859 ("kvm: Use struct_size() in kmalloc()")
    d4c67a7a54f1 ("kvm: use insert sort in kvm_io_bus_register_dev function")
    d62caabb41f3 ("kvm/x86: per-vcpu apicv deactivation support")


NOTE: The patch will not be queued to stable trees until it is upstream.

How should we proceed with this patch?

-- 
Thanks
Sasha

Re: [PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[Paolo Bonzini]

On 19/09/20 02:09, Gustavo A. R. Silva wrote:
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Queued, without stable.  Thanks.

Paolo

Re: [PATCH] KVM: use struct_size() and flex_array_size() helpers in kvm_io_bus_unregister_dev()

[Gustavo A. R. Silva]

Hi Sasha,

On 9/21/20 07:54, Sasha Levin wrote:

> 
> NOTE: The patch will not be queued to stable trees until it is upstream.
> 
> How should we proceed with this patch?
> 

This patch should not go to -stable.

The author has resent it without the _stable_ stag.

Thanks
--
Gustavo