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KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots

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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>
[mpe: Use 'size' for the variable rather than 'cb']
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210901084512.1658628-1-aik@ozlabs.ru
This commit is contained in:
Alexey Kardashevskiy 2021-09-01 18:45:12 +10:00 committed by Michael Ellerman
parent f6a1987773
commit 511d25d6b7
1 changed files with 6 additions and 2 deletions
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8
arch/powerpc/kvm/book3s_hv.c
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@ -4872,8 +4872,12 @@ 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 size = array_size(npages, sizeof(*slot->arch.rmap));
if ((size >> PAGE_SHIFT) > totalram_pages())
return -ENOMEM;
slot->arch.rmap = vzalloc(size);
if (!slot->arch.rmap)
return -ENOMEM;
}