From: Greg Kroah-Hartman gregkh@linuxfoundation.org
[ Upstream commit 8ed0579c12b2fe56a1fac2f712f58fc26c1dc49b ]
debugfs can now report an error code if something went wrong instead of just NULL. So if the return value is to be used as a "real" dentry, it needs to be checked if it is an error before dereferencing it.
This is now happening because of ff9fb72bc077 ("debugfs: return error values, not NULL"). syzbot has found a way to trigger multiple debugfs files attempting to be created, which fails, and then the error code gets passed to dentry_path_raw() which obviously does not like it.
Reported-by: Eric Biggers ebiggers@kernel.org Reported-and-tested-by: syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com Cc: "Radim Krčmář" rkrcmar@redhat.com Cc: kvm@vger.kernel.org Acked-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c436d95fd7aa..fb74f994cb63 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3912,7 +3912,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm) } add_uevent_var(env, "PID=%d", kvm->userspace_pid);
- if (kvm->debugfs_dentry) { + if (!IS_ERR_OR_NULL(kvm->debugfs_dentry)) { char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL);
if (p) {