From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa1-x35.google.com (mail-oa1-x35.google.com [IPv6:2001:4860:4864:20::35]) by sourceware.org (Postfix) with ESMTPS id 2A0DA384F480; Wed, 23 Nov 2022 22:21:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2A0DA384F480 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-oa1-x35.google.com with SMTP id 586e51a60fabf-14263779059so87225fac.1; Wed, 23 Nov 2022 14:21:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=TlF45W5kuDOrmFlNTy8fVJ2ax8tCd46eLsTAKK7W5JM=; b=YAY68DG5eEEgY04rocu4l614aUquQnTnjOQp14J3tA4yhQ+aSVbjGoDWjHHUfREPkc WcMkuKoEOJLnDiSF/rJ6moPrWweQF23sGYvbDsIvWNGL6OgdWYEFZ5fJLMAcXiaiE1IY f4JlNoXuoUT6WumedxaHEdyyHdwR5KB+PNUjlnOeodindeCNBF51V/a0z0kd0dwV8zFq NDhf/OcOOry3FAcdMYvOirTf2KKLWE00h2KYqJLU1PJ3jIbLzGsYFUWHIaKzIBmAddVF AssVTsz2zylTf7XJhES1GNfeUao1+Mwjx06xqLBoOyR/NMTf40ZVh7QMXakaBuGRlAuq +yzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=TlF45W5kuDOrmFlNTy8fVJ2ax8tCd46eLsTAKK7W5JM=; b=rxH1DL76nILyejplJCWSIskNZtSuMDQdtwGvg0ZOnSp/QN5PokLpEDa2iyHlB+6862 cfJxTHAxNvj+3pAK6rfWesN73uQEarpu+S86UIhb9NjyIJngmEV1fRQsKrLm5KmW4NHo 2Q6/KbiNSWRQVRm62hZmcxuX/3rviq2pVB9g1RNehwNQKaWE+mYGZAZSnfJVRK030Znq qukyznqJTqGgeubE7dd94R7Y1VH5JO8pvzqpLDPHNm1a6Pr42IKFPXcBFm1wKbo1k/al UI8vFgz+Z4uhZVgOe14TuJQqqt5dMZFJppcxjS9iJu5LHerZWbqvzMhb/b/McXbHVMI4 bsqg== X-Gm-Message-State: ANoB5pm3V6orqpR3M6osgxOr1JIA6EugIt8SbAsqo6AlfQ+FN146aby4 PgM9KYyAP/gFA+XHmpNK1cK4mlyy/TgpD2diO/c= X-Google-Smtp-Source: AA0mqf5kp5gXbgclgXVzNADCiO3tkZvX4vfrpiHOWXeEb3BvbJlsHx9iqxv/00MrefmTb9jXCRfsWmcOidoDFYhW62U= X-Received: by 2002:a05:6870:4720:b0:13c:2ced:9d9a with SMTP id b32-20020a056870472000b0013c2ced9d9amr7471432oaq.105.1669242085363; Wed, 23 Nov 2022 14:21:25 -0800 (PST) MIME-Version: 1.0 References: <20220921005804.7131-1-goldstein.w.n@gmail.com> In-Reply-To: From: Sunil Pandey Date: Wed, 23 Nov 2022 14:20:49 -0800 Message-ID: Subject: Re: [PATCH v1] x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591] To: "H.J. Lu" , Libc-stable Mailing List Cc: Noah Goldstein , libc-alpha@sourceware.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-6.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,GIT_PATCH_0,HK_RANDOM_ENVFROM,HK_RANDOM_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha wrote: > > On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein wrote: > > > > Previous implementation was adjusting length (rsi) to match > > bytes (eax), but since there is no bound to length this can cause > > overflow. > > > > Fix is to just convert the byte-count (eax) to length by dividing by > > sizeof (wchar_t) before the comparison. > > > > Full check passes on x86-64 and build succeeds w/ and w/o multiarch. > > --- > > string/test-strnlen.c | 70 +++++++++++++++----------- > > sysdeps/x86_64/multiarch/strlen-avx2.S | 7 +-- > > 2 files changed, 43 insertions(+), 34 deletions(-) > > > > diff --git a/string/test-strnlen.c b/string/test-strnlen.c > > index 4a9375112a..5cbaf4b734 100644 > > --- a/string/test-strnlen.c > > +++ b/string/test-strnlen.c > > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char) > > { > > size_t i; > > > > - align &= 63; > > + align &= (getpagesize () / sizeof (CHAR) - 1); > > if ((align + len) * sizeof (CHAR) >= page_size) > > return; > > > > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char) > > static void > > do_overflow_tests (void) > > { > > - size_t i, j, len; > > + size_t i, j, al_idx, repeats, len; > > const size_t one = 1; > > uintptr_t buf_addr = (uintptr_t) buf1; > > + const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 }; > > > > - for (i = 0; i < 750; ++i) > > + for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]); > > + al_idx++) > > { > > - do_test (1, i, SIZE_MAX, BIG_CHAR); > > - > > - do_test (0, i, SIZE_MAX - i, BIG_CHAR); > > - do_test (0, i, i - buf_addr, BIG_CHAR); > > - do_test (0, i, -buf_addr - i, BIG_CHAR); > > - do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR); > > - do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR); > > - > > - len = 0; > > - for (j = 8 * sizeof(size_t) - 1; j ; --j) > > - { > > - len |= one << j; > > - do_test (0, i, len - i, BIG_CHAR); > > - do_test (0, i, len + i, BIG_CHAR); > > - do_test (0, i, len - buf_addr - i, BIG_CHAR); > > - do_test (0, i, len - buf_addr + i, BIG_CHAR); > > - > > - do_test (0, i, ~len - i, BIG_CHAR); > > - do_test (0, i, ~len + i, BIG_CHAR); > > - do_test (0, i, ~len - buf_addr - i, BIG_CHAR); > > - do_test (0, i, ~len - buf_addr + i, BIG_CHAR); > > - > > - do_test (0, i, -buf_addr, BIG_CHAR); > > - do_test (0, i, j - buf_addr, BIG_CHAR); > > - do_test (0, i, -buf_addr - j, BIG_CHAR); > > - } > > + for (repeats = 0; repeats < 2; ++repeats) > > + { > > + size_t align = repeats ? (getpagesize () - alignments[al_idx]) > > + : alignments[al_idx]; > > + align /= sizeof (CHAR); > > + for (i = 0; i < 750; ++i) > > + { > > + do_test (align, i, SIZE_MAX, BIG_CHAR); > > + > > + do_test (align, i, SIZE_MAX - i, BIG_CHAR); > > + do_test (align, i, i - buf_addr, BIG_CHAR); > > + do_test (align, i, -buf_addr - i, BIG_CHAR); > > + do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR); > > + do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR); > > + > > + len = 0; > > + for (j = 8 * sizeof (size_t) - 1; j; --j) > > + { > > + len |= one << j; > > + do_test (align, i, len, BIG_CHAR); > > + do_test (align, i, len - i, BIG_CHAR); > > + do_test (align, i, len + i, BIG_CHAR); > > + do_test (align, i, len - buf_addr - i, BIG_CHAR); > > + do_test (align, i, len - buf_addr + i, BIG_CHAR); > > + > > + do_test (align, i, ~len - i, BIG_CHAR); > > + do_test (align, i, ~len + i, BIG_CHAR); > > + do_test (align, i, ~len - buf_addr - i, BIG_CHAR); > > + do_test (align, i, ~len - buf_addr + i, BIG_CHAR); > > + > > + do_test (align, i, -buf_addr, BIG_CHAR); > > + do_test (align, i, j - buf_addr, BIG_CHAR); > > + do_test (align, i, -buf_addr - j, BIG_CHAR); > > + } > > + } > > + } > > } > > } > > > > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S > > index 0593fb303b..b9b58ef599 100644 > > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S > > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S > > @@ -544,14 +544,11 @@ L(return_vzeroupper): > > L(cross_page_less_vec): > > tzcntl %eax, %eax > > # ifdef USE_AS_WCSLEN > > - /* NB: Multiply length by 4 to get byte count. */ > > - sall $2, %esi > > + /* NB: Divide by 4 to convert from byte-count to length. */ > > + shrl $2, %eax > > # endif > > cmpq %rax, %rsi > > cmovb %esi, %eax > > -# ifdef USE_AS_WCSLEN > > - shrl $2, %eax > > -# endif > > VZEROUPPER_RETURN > > # endif > > > > -- > > 2.34.1 > > > > LGTM. > > Thanks. > > -- > H.J. I would like to backport this patch to affected release branches from 2.36 to 2.33. Any comments/suggestions or objections on this. --Sunil