Hello Kuniyuki Iwashima,
Commit a74712241b46 ("selftest: bpf: Test
bpf_sk_assign_tcp_reqsk().") from Jan 15, 2024 (linux-next), leads to
the following Smatch static checker warning:
tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c:493 tcp_validate_cookie()
warn: off by one 'mssind' == ARRAY_SIZE()?
./tools/testing/selftests/bpf/progs/test_tcp_custom_syncookie.c
462 static int tcp_validate_cookie(struct tcp_syncookie *ctx)
463 {
464 u32 cookie = bpf_ntohl(ctx->tcp->ack_seq) - 1;
465 u32 seq = bpf_ntohl(ctx->tcp->seq) - 1;
466 u64 first = 0, second;
467 int mssind;
468 u32 hash;
469
470 if (ctx->ipv4)
471 first = (u64)ctx->ipv4->saddr << 32 | ctx->ipv4->daddr;
472 else if (ctx->ipv6)
473 first = (u64)ctx->ipv6->saddr.in6_u.u6_addr8[0] << 32 |
474 ctx->ipv6->daddr.in6_u.u6_addr32[0];
475
476 second = (u64)seq << 32 | ctx->tcp->source << 16 | ctx->tcp->dest;
477 hash = siphash_2u64(first, second, &test_key_siphash);
478
479 if (ctx->attrs.tstamp_ok)
480 hash -= ctx->attrs.rcv_tsecr & COOKIE_MASK;
481 else
482 hash &= ~COOKIE_MASK;
483
484 hash -= cookie & ~COOKIE_MASK;
485 if (hash)
486 goto err;
487
488 mssind = (cookie & (3 << 6)) >> 6;
489 if (ctx->ipv4) {
490 if (mssind > ARRAY_SIZE(msstab4))
^
Should be >= instead of >.
491 goto err;
492
--> 493 ctx->attrs.mss = msstab4[mssind];
494 } else {
495 if (mssind > ARRAY_SIZE(msstab6))
496 goto err;
497
498 ctx->attrs.mss = msstab6[mssind];
499 }
500
501 ctx->attrs.snd_wscale = cookie & BPF_SYNCOOKIE_WSCALE_MASK;
502 ctx->attrs.rcv_wscale = ctx->attrs.snd_wscale;
503 ctx->attrs.wscale_ok = ctx->attrs.snd_wscale == BPF_SYNCOOKIE_WSCALE_MASK;
504 ctx->attrs.sack_ok = cookie & BPF_SYNCOOKIE_SACK;
505 ctx->attrs.ecn_ok = cookie & BPF_SYNCOOKIE_ECN;
506
507 return 0;
508 err:
509 return -1;
510 }
regards,
dan carpenter
