From: Alexei Starovoitov <a...@fb.com> Date: Sat, 29 Apr 2017 22:52:42 -0700
> From: Yonghong Song <y...@fb.com> > > llvm 4.0 and above generates the code like below: > .... > 440: (b7) r1 = 15 > 441: (05) goto pc+73 > 515: (79) r6 = *(u64 *)(r10 -152) > 516: (bf) r7 = r10 > 517: (07) r7 += -112 > 518: (bf) r2 = r7 > 519: (0f) r2 += r1 > 520: (71) r1 = *(u8 *)(r8 +0) > 521: (73) *(u8 *)(r2 +45) = r1 > .... > and the verifier complains "R2 invalid mem access 'inv'" for insn #521. > This is because verifier marks register r2 as unknown value after #519 > where r2 is a stack pointer and r1 holds a constant value. > > Teach verifier to recognize "stack_ptr + imm" and > "stack_ptr + reg with const val" as valid stack_ptr with new offset. > > Signed-off-by: Yonghong Song <y...@fb.com> > Acked-by: Martin KaFai Lau <ka...@fb.com> > Acked-by: Daniel Borkmann <dan...@iogearbox.net> > Signed-off-by: Alexei Starovoitov <a...@kernel.org> > --- > technically it's 'net' material, but it's too late for 'net', > hence 'net-next' tag. > No 'Fixes' tag, since it's only seen with newer llvm. Applied to net-next, but I'll queue this up to -stable.
