This is a note to let you know that I've just added the patch titled KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-ppc-book3s-suppress-warnings-when-allocating-too.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 1d1768f15a7d279d8c5f0c28a2aa1b8f77c919aa Author: Alexey Kardashevskiy <aik@xxxxxxxxx> Date: Wed Sep 1 18:45:12 2021 +1000 KVM: PPC: Book3S: Suppress warnings when allocating too big memory slots [ Upstream commit 511d25d6b789fffcb20a3eb71899cf974a31bd9d ] 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@xxxxxxxxx> [mpe: Use 'size' for the variable rather than 'cb'] Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210901084512.1658628-1-aik@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 175967a195c44..527c205d5a5f5 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -4557,8 +4557,12 @@ 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; }