Messages in this thread | | | Date | Tue, 12 Oct 2021 09:34:29 +0800 | From | Li Fei1 <> | Subject | Re: [PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic |
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On Mon, Oct 11, 2021 at 12:39:02PM +0200, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the array_size() helper to do the arithmetic instead of the > argument "count * size" in the vzalloc() function. > > Also, take the opportunity to add a flexible array member of struct > vm_memory_region_op to the vm_memory_region_batch structure. And then, > change the code accordingly and use the struct_size() helper to do the > arithmetic instead of the argument "size + size * count" in the kzalloc > function. > > This code was detected with the help of Coccinelle and audited and fixed > manually. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com>
Hi Baker
Thanks for helping us to fix this issue. This patch looks good to me. Please add Signed-off-by: Fei Li <fei1.li@intel.com>. Only two minor comments.
> --- > drivers/virt/acrn/acrn_drv.h | 10 ++++++---- > drivers/virt/acrn/mm.c | 9 ++++----- > 2 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h > index 1be54efa666c..fcc2e3e5232a 100644 > --- a/drivers/virt/acrn/acrn_drv.h > +++ b/drivers/virt/acrn/acrn_drv.h > @@ -48,6 +48,7 @@ struct vm_memory_region_op { > * @reserved: Reserved. > * @regions_num: The number of vm_memory_region_op. > * @regions_gpa: Physical address of a vm_memory_region_op array. > + * @regions_op: Flexible array of vm_memory_region_op. One Tab please. > * > * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of > * multiple memory regions of a User VM. A &struct vm_memory_region_batch > @@ -55,10 +56,11 @@ struct vm_memory_region_op { > * ACRN Hypervisor. > */ > struct vm_memory_region_batch { > - u16 vmid; > - u16 reserved[3]; > - u32 regions_num; > - u64 regions_gpa; > + u16 vmid; > + u16 reserved[3]; > + u32 regions_num; > + u64 regions_gpa; > + struct vm_memory_region_op regions_op[]; Please use Whitespace instead of Tab. > }; > > /** > diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c > index c4f2e15c8a2b..a881742cd48d 100644 > --- a/drivers/virt/acrn/mm.c > +++ b/drivers/virt/acrn/mm.c > @@ -168,7 +168,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap) > > /* Get the page number of the map region */ > nr_pages = memmap->len >> PAGE_SHIFT; > - pages = vzalloc(nr_pages * sizeof(struct page *)); > + pages = vzalloc(array_size(nr_pages, sizeof(struct page *))); > if (!pages) > return -ENOMEM; > > @@ -220,16 +220,15 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap) > } > > /* Prepare the vm_memory_region_batch */ > - regions_info = kzalloc(sizeof(*regions_info) + > - sizeof(*vm_region) * nr_regions, > - GFP_KERNEL); > + regions_info = kzalloc(struct_size(regions_info, regions_op, > + nr_regions), GFP_KERNEL); > if (!regions_info) { > ret = -ENOMEM; > goto unmap_kernel_map; > } > > /* Fill each vm_memory_region_op */ > - vm_region = (struct vm_memory_region_op *)(regions_info + 1); > + vm_region = regions_info->regions_op; > regions_info->vmid = vm->vmid; > regions_info->regions_num = nr_regions; > regions_info->regions_gpa = virt_to_phys(vm_region); > -- > 2.25.1 >
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