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[176.36.0.241]) by smtp.gmail.com with ESMTPSA id fj25-20020a0564022b9900b00556cd818dd2sm1603946edb.70.2024.01.03.18.27.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jan 2024 18:27:06 -0800 (PST) Message-ID: Subject: Re: [PATCH bpf-next 12/15] bpf: Preserve boundaries and track scalars on narrowing fill From: Eduard Zingerman To: Maxim Mikityanskiy Cc: bpf@vger.kernel.org Date: Thu, 04 Jan 2024 04:27:00 +0200 In-Reply-To: <20231220214013.3327288-13-maxtram95@gmail.com> References: <20231220214013.3327288-1-maxtram95@gmail.com> <20231220214013.3327288-13-maxtram95@gmail.com> Autocrypt: addr=eddyz87@gmail.com; prefer-encrypt=mutual; keydata=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 nYzhLWGcczc6J71q1Dje0l5vIPaSFOgwmWD4DA+WvuxM/shH4rtWeodbv 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 t1iq+gsfnXbPz5AnS598ScZI1oP7OrPSFJkt/z4acEbOQDQs8aUqrd46PV jsdqGvKnXZxzylux29UTNby4jTlz9pNJM+wPrDRmGfchLDUmf6CffaUYCbu4FiId+9+dcTCDvxbABRy1C3OJ8QY7cxfJ+pEZW18fRJ0XCl/fiV/ecAOfB3HsqgTzAn555h0rkFgay0hAvMU/mAW/CFNSIxV397zm749ZNLA0L2dMy1AKuOqH+/B+/ImBfJMDjmdyJQ8WU/OFRuGLdqOd2oZrA1iuPIa+yUYyZkaZfz/emQwpIL1+Q4p1R/OplA4yc301AqruXXUcVDbEB+joHW3hy5FwK5t5OwTKatrSJBkydSF9zdXy98fYzGniRyRA65P0Ix/8J3BYB4edY2/w0Ip/mdYsYQljBY0A== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.2 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2023-12-20 at 23:40 +0200, Maxim Mikityanskiy wrote: [...] The two tests below were added by the following commit: ef979017b837 ("bpf: selftest: Add verifier tests for <8-byte scalar spill a= nd refill") As far as I understand, the original intent was to check the behavior for stack read/write with non-matching size. I think these tests are redundant after patch #13. Wdyt? > diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/to= ols/testing/selftests/bpf/progs/verifier_spill_fill.c > index 809a09732168..de03e72e07a9 100644 > --- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c > +++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c > @@ -217,7 +217,7 @@ __naked void uninit_u32_from_the_stack(void) > =20 > SEC("tc") > __description("Spill a u32 const scalar. Refill as u16. Offset to skb-= >data") > -__failure __msg("invalid access to packet") > +__success __retval(0) > __naked void u16_offset_to_skb_data(void) > { > asm volatile (" \ > @@ -225,19 +225,24 @@ __naked void u16_offset_to_skb_data(void) > r3 =3D *(u32*)(r1 + %[__sk_buff_data_end]); \ > w4 =3D 20; \ > *(u32*)(r10 - 8) =3D r4; \ > - r4 =3D *(u16*)(r10 - 8); \ > + r4 =3D *(u16*)(r10 - %[offset]); \ > r0 =3D r2; \ > - /* r0 +=3D r4 R0=3Dpkt R2=3Dpkt R3=3Dpkt_end R4=3Dumax=3D65535 */\ > + /* r0 +=3D r4 R0=3Dpkt R2=3Dpkt R3=3Dpkt_end R4=3D20 */\ > r0 +=3D r4; \ > - /* if (r0 > r3) R0=3Dpkt,umax=3D65535 R2=3Dpkt R3=3Dpkt_end R4=3Dumax= =3D65535 */\ > + /* if (r0 > r3) R0=3Dpkt,off=3D20 R2=3Dpkt R3=3Dpkt_end R4=3D20 */\ > if r0 > r3 goto l0_%=3D; \ > - /* r0 =3D *(u32 *)r2 R0=3Dpkt,umax=3D65535 R2=3Dpkt R3=3Dpkt_end R4=3D2= 0 */\ > + /* r0 =3D *(u32 *)r2 R0=3Dpkt,off=3D20 R2=3Dpkt R3=3Dpkt_end R4=3D20 */= \ > r0 =3D *(u32*)(r2 + 0); \ > l0_%=3D: r0 =3D 0; \ > exit; \ > " : > : __imm_const(__sk_buff_data, offsetof(struct __sk_buff, data)), > - __imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end)) > + __imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end))= , > +#if __BYTE_ORDER__ =3D=3D __ORDER_LITTLE_ENDIAN__ > + __imm_const(offset, 8) > +#else > + __imm_const(offset, 6) > +#endif > : __clobber_all); > } > =20 > @@ -270,7 +275,7 @@ l0_%=3D: r0 =3D 0; \ > } > =20 > SEC("tc") > -__description("Spill a u32 const scalar. Refill as u16 from fp-6. Offs= et to skb->data") > +__description("Spill a u32 const scalar. Refill as u16 from MSB. Offse= t to skb->data") > __failure __msg("invalid access to packet") > __naked void _6_offset_to_skb_data(void) > { > @@ -279,7 +284,7 @@ __naked void _6_offset_to_skb_data(void) > r3 =3D *(u32*)(r1 + %[__sk_buff_data_end]); \ > w4 =3D 20; \ > *(u32*)(r10 - 8) =3D r4; \ > - r4 =3D *(u16*)(r10 - 6); \ > + r4 =3D *(u16*)(r10 - %[offset]); \ > r0 =3D r2; \ > /* r0 +=3D r4 R0=3Dpkt R2=3Dpkt R3=3Dpkt_end R4=3Dumax=3D65535 */\ > r0 +=3D r4; \ > @@ -291,7 +296,12 @@ l0_%=3D: r0 =3D 0; \ > exit; \ > " : > : __imm_const(__sk_buff_data, offsetof(struct __sk_buff, data)), > - __imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end)) > + __imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end))= , > +#if __BYTE_ORDER__ =3D=3D __ORDER_LITTLE_ENDIAN__ > + __imm_const(offset, 6) > +#else > + __imm_const(offset, 8) > +#endif > : __clobber_all); > } > =20