hv: Fix issue in size used for memset in create_vm #5108
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No new violations to the coding guideline detected. |
arch_vm member of struct acrn_vm is page aligned. memset used in create_vm subtracts only 8 bytes, sizeof(spinlock_t) from the size of acrn_vm and uses the vm->arch_vm as the destination address. To do it right, it should subtract 4096 bytes. This would result in writing memory beyond the acrn_vm struct. This patch fixes the issue by using offsetof compiler macro and subtracts the right amount of size corresponding to the beginning of arch_vm member in struct acrn_vm. Tracked-On: projectacrn#5107 Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
dongyaozu
reviewed
Jul 30, 2020
| * subtracting 4K from the total size of acrn_vm. | ||
| * Using offset_of macro to avoid hardcoding 4k here. | ||
| */ | ||
| (void)memset((void *)&vm->arch_vm, 0U, (sizeof(struct acrn_vm) - offsetof(struct acrn_vm, arch_vm))); |
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I see. What we want to reset is from arch_vm to the end of vm structure.
Will " (size_t *) (vm+1) - (size_t) &vm->arch_vm" be easier to reader?
You decide.
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Oh, the current definition of struct acrn_vm may waste ~1 page of memory. We need a cleaner solution.
dongyaozu
approved these changes
Jul 30, 2020
dongyaozu
requested changes
Jul 30, 2020
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@sainath14 please rebase your code, thanks |
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This is not needed after #5128 |
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arch_vm member of struct acrn_vm is page aligned. memset used in create_vm
subtracts only 8 bytes, sizeof(spinlock_t) from the size of acrn_vm and uses
the vm->arch_vm as the destination address. To do it right, it should subtract
4096 bytes. This would result in writing memory beyond the acrn_vm struct.
This patch fixes the issue by using offsetof compiler macro and subtracts the
right amount of size corresponding to the beginning of arch_vm member in
struct acrn_vm.
Tracked-On: #5107
Signed-off-by: Sainath Grandhi sainath.grandhi@intel.com