Re: [PATCH stable 6.6 07/10] bpf: consider that tail calls invalidate packet pointers

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 1a4607ffba35bf2a630aab299e34dd3f6e658d70

WARNING: Author mismatch between patch and upstream commit:
Backport author: Shung-Hsi Yu<shung-hsi.yu@suse.com>
Commit author: Eduard Zingerman<eddyz87@gmail.com>

Status in newer kernel trees:
6.14.y | Present (exact SHA1)
6.12.y | Present (different SHA1: 1c2244437f9a)

Note: The patch differs from the upstream commit:
---
1:  1a4607ffba35b ! 1:  ab43ca5545f85 bpf: consider that tail calls invalidate packet pointers
    @@ Metadata
      ## Commit message ##
         bpf: consider that tail calls invalidate packet pointers
     
    +    commit 1a4607ffba35bf2a630aab299e34dd3f6e658d70 upstream.
    +
         Tail-called programs could execute any of the helpers that invalidate
         packet pointers. Hence, conservatively assume that each tail call
         invalidates packet pointers.
    @@ Commit message
         Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
         Link: https://lore.kernel.org/r/20241210041100.1898468-8-eddyz87@gmail.com
         Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    +    [ shung-hsi.yu: drop changes to tools/testing/selftests/bpf/progs/tc_bpf2bpf.c
    +    because it is not present. ]
    +    Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
     
      ## net/core/filter.c ##
     @@ net/core/filter.c: bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id)
    @@ net/core/filter.c: bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id)
      		return true;
      	default:
      		return false;
    -
    - ## tools/testing/selftests/bpf/progs/tc_bpf2bpf.c ##
    -@@ tools/testing/selftests/bpf/progs/tc_bpf2bpf.c: int subprog_tc(struct __sk_buff *skb)
    - 
    - 	__sink(skb);
    - 	__sink(ret);
    -+	/* let verifier know that 'subprog_tc' can change pointers to skb->data */
    -+	bpf_skb_change_proto(skb, 0, 0);
    - 	return ret;
    - }
    - 
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Success    |  Success   |