On Wed, 2025-07-02 at 10:11 -0700, Yonghong Song wrote: > Arnd Bergmann reported an issue ([1]) where clang compiler (less than > llvm18) may trigger an error where the stack frame size exceeds the limit. > I can reproduce the error like below: > kernel/bpf/verifier.c:24491:5: error: stack frame size (2552) exceeds limit (1280) in 'bpf_check' > [-Werror,-Wframe-larger-than] > kernel/bpf/verifier.c:19921:12: error: stack frame size (1368) exceeds limit (1280) in 'do_check' > [-Werror,-Wframe-larger-than] > > Use env->insn_buf for bpf insns instead of putting these insns on the > stack. This can resolve the above 'bpf_check' error. The 'do_check' error > will be resolved in the next patch. > > [1] https://lore.kernel.org/bpf/20250620113846.3950478-1-arnd@xxxxxxxxxx/ > > Reported-by: Arnd Bergmann <arnd@xxxxxxxxxx> > Tested-by: Arnd Bergmann <arnd@xxxxxxxx> > Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> > Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx> > --- Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx> > kernel/bpf/verifier.c | 189 ++++++++++++++++++++---------------------- > 1 file changed, 91 insertions(+), 98 deletions(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 8b0a25851089..ef53e313d841 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -21010,7 +21010,9 @@ static int opt_remove_nops(struct bpf_verifier_env *env) > static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env, > const union bpf_attr *attr) > { > - struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4]; > + struct bpf_insn *patch; > + struct bpf_insn *zext_patch = env->insn_buf; > + struct bpf_insn *rnd_hi32_patch = &env->insn_buf[2]; Nit: I'd add a comment here, something along the lines: "use env->insn_buf as two independent buffers" > struct bpf_insn_aux_data *aux = env->insn_aux_data; > int i, patch_len, delta = 0, len = env->prog->len; > struct bpf_insn *insns = env->prog->insnsi; [...]
