Re: [PATCH 6.1.y v2 1/6] bpf: allow precision tracking for programs with subprogs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jun 25, 2024 at 03:28:31PM +0800, Shung-Hsi Yu wrote:
> Hi Greg,
> 
> On Mon, Jul 24, 2023 at 03:42:18PM GMT, Eduard Zingerman wrote:
> > [ Upstream commit be2ef8161572ec1973124ebc50f56dafc2925e07 ]
> > 
> ...
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> ...
> > @@ -2670,6 +2679,11 @@ static int backtrack_insn(struct bpf_verifier_env *env, int idx,
> >  			 */
> >  			if (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && insn->imm == 0)
> >  				return -ENOTSUPP;
> > +			/* BPF helpers that invoke callback subprogs are
> > +			 * equivalent to BPF_PSEUDO_CALL above
> > +			 */
> > +			if (insn->src_reg == 0 && is_callback_calling_function(insn->imm))
> > +				return -ENOTSUPP;
> >  			/* regular helper call sets R0 */
> >  			*reg_mask &= ~1;
> >  			if (*reg_mask & 0x3f) {
> 
> Looks like the above hunk is slightly misplaced.
> 
> In master the lines are added _before_ the BPF_PSEUDO_KFUNC_CALL check,
> resulting in deviation from upstream as well as interfering with
> backporting of commit be2ef8161572 ("bpf: allow precision tracking for
> programs with subprogs") to stable v6.1.
> 
> What would be the suggested action here?
> 1. Send a updated version of the whole be2ef8161572 patch to stable
> 2. Send a minimal refresh patch like the one found in this email to
>    stable
> 3. Adapt to this deviation in my backport of commit be2ef8161572 for
>    stable

Please send a fix-up patch for this as I can't change the existing
releases.

thanks,

greg k-h