From 5c1f50ab7fcb4e77a0b4ce102cfb890eef1ed8f1 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Thu, 13 Jun 2024 17:33:16 +0300 Subject: [PATCH] KVM: Fix a goof where kvm_create_vm() returns 0 instead of -ENOMEM The error path for OOM when allocating buses used to return -ENOMEM using the local variable 'r', where 'r' was initialized at the top of the function. But a new "r = kvm_init_irq_routing(kvm);" was introduced in the middle of the function, so now the error code is not set and it eventually leads to a NULL dereference due to kvm_dev_ioctl_create_vm() thinking kvm_create_vm() succeeded. Set the error code back to -ENOMEM. Opportunistically tweak the logic to pre-set "r = -ENOMEM" immediately before the flows that can fail due to memory allocation failure to make it less likely that the bug recurs in the future. Fixes: fbe4a7e881d4 ("KVM: Setup empty IRQ routing when creating a VM") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/02051e0a-09d8-49a2-917f-7c2f278a1ba1@moroto.mountain [sean: tweak all of the "r = -ENOMEM" sites, massage changelog] Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b60186b9c1d3..436ca41f61e5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1143,8 +1143,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) { struct kvm *kvm = kvm_arch_alloc_vm(); struct kvm_memslots *slots; - int r = -ENOMEM; - int i, j; + int r, i, j; if (!kvm) return ERR_PTR(-ENOMEM); @@ -1181,6 +1180,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) snprintf(kvm->stats_id, sizeof(kvm->stats_id), "kvm-%d", task_pid_nr(current)); + r = -ENOMEM; if (init_srcu_struct(&kvm->srcu)) goto out_err_no_srcu; if (init_srcu_struct(&kvm->irq_srcu)) @@ -1209,6 +1209,7 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname) rcu_assign_pointer(kvm->memslots[i], &kvm->__memslots[i][0]); } + r = -ENOMEM; for (i = 0; i < KVM_NR_BUSES; i++) { rcu_assign_pointer(kvm->buses[i], kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL_ACCOUNT)); -- 2.50.1