KVM: Harden copying of userspace-array against overflow

kvm_main.c utilizes vmemdup_user() and array_size() to copy a userspace
array. Currently, this does not check for an overflow.

Use the new wrapper vmemdup_array_user() to copy the array more safely.

Note, KVM explicitly checks the number of entries before duplicating the
array, i.e. adding the overflow check should be a glorified nop.

Suggested-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Link: https://lore.kernel.org/r/20231102181526.43279-4-pstanner@redhat.com
[sean: call out that KVM pre-checks the number of entries]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Philipp Stanner 2023-11-02 19:15:26 +01:00 committed by Sean Christopherson
parent 8c4976772d
commit 1f829359c8

View file

@ -5262,9 +5262,8 @@ static long kvm_vm_ioctl(struct file *filp,
goto out;
if (routing.nr) {
urouting = argp;
entries = vmemdup_user(urouting->entries,
array_size(sizeof(*entries),
routing.nr));
entries = vmemdup_array_user(urouting->entries,
routing.nr, sizeof(*entries));
if (IS_ERR(entries)) {
r = PTR_ERR(entries);
goto out;