From 8ed0579c12b2fe56a1fac2f712f58fc26c1dc49b Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 28 Feb 2019 16:34:37 +0100 Subject: kvm: properly check debugfs dentry before using it 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 Reported-and-tested-by: syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com Cc: "Radim Krčmář" Cc: kvm@vger.kernel.org Acked-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 585845203db8..076bc38963bf 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4044,7 +4044,7 @@ 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) { -- cgit v1.2.3