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| author | David Gibson <david@gibson.dropbear.id.au> | 2017-02-15 14:40:04 +1100 |
|---|---|---|
| committer | Paul Mackerras <paulus@ozlabs.org> | 2017-02-16 16:32:19 +1100 |
| commit | 5b73d6347eb82cd2a26698fc339607e25e0ad917 (patch) | |
| tree | 9895be307c2cdaf2dbe3ac393d5506fe20aa9ac5 /arch/powerpc | |
| parent | ee10689117c0186fd4fe7feca8d48c7316f65d70 (diff) | |
| download | linux-5b73d6347eb82cd2a26698fc339607e25e0ad917.tar.gz linux-5b73d6347eb82cd2a26698fc339607e25e0ad917.tar.xz | |
KVM: PPC: Book3S HV: Prevent double-free on HPT resize commit path
resize_hpt_release(), called once the HPT resize of a KVM guest is
completed (successfully or unsuccessfully) frees the state structure for
the resize. It is currently not safe to call with a NULL pointer.
However, one of the error paths in kvm_vm_ioctl_resize_hpt_commit() can
invoke it with a NULL pointer. This will occur if userspace improperly
invokes KVM_PPC_RESIZE_HPT_COMMIT without previously calling
KVM_PPC_RESIZE_HPT_PREPARE, or if it calls COMMIT twice without an
intervening PREPARE.
To fix this potential crash bug - and maybe others like it, make it safe
(and a no-op) to call resize_hpt_release() with a NULL resize pointer.
Found by Dan Carpenter with a static checker.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kvm/book3s_64_mmu_hv.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 013552f05182..72ccac26e464 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -1407,6 +1407,9 @@ static void resize_hpt_release(struct kvm *kvm, struct kvm_resize_hpt *resize) { BUG_ON(kvm->arch.resize_hpt != resize); + if (!resize) + return; + if (resize->hpt.virt) kvmppc_free_hpt(&resize->hpt); |