On Fri, Mar 29, 2019 at 09:28:33PM -0400, Sasha Levin wrote: > From: Greg Kroah-Hartman <[email protected]> > > [ 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 <[email protected]> > Reported-and-tested-by: [email protected] > Cc: "Radim Krčmář" <[email protected]> > Cc: [email protected] > Acked-by: Paolo Bonzini <[email protected]> > Signed-off-by: Greg Kroah-Hartman <[email protected]> > Signed-off-by: Linus Torvalds <[email protected]> > Signed-off-by: Sasha Levin <[email protected]> > --- > 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) { > -- > 2.19.1 >
Same thing here, this was a 5.0-only thing, no need for it to be backported, please drop it from all trees. thanks, greg k-h
