From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 7844) id 7995F3858D1E; Thu, 29 Sep 2022 03:38:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7995F3858D1E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1664422734; bh=DtPZxEdrfvP4t0NzJGv6IDV+JMuvC5XnX4TyVW2IttE=; h=From:To:Subject:Date:From; b=V4EmZknV7m7E2zCLbWJ5A+qdXvb//KvBj0uV28UXUEQf2lfJVKuXZGjlNZldM4hmd wf+Xp2qGyoDf1c9yXt77XxV/rtvbyu/l5qGJDdhGVowJMBs+0SeajOdGZ8IkH63O0o JZHTJ0+HPks3wdF8FRfO2219vTPZZAF2clr1K/7M= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Noah Goldstein To: glibc-cvs@sourceware.org Subject: [glibc] x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591] X-Act-Checkin: glibc X-Git-Author: Noah Goldstein X-Git-Refname: refs/heads/master X-Git-Oldrev: 3e5760fcb48528d48deeb60cb885a97bb731160c X-Git-Newrev: b0969fa53a28b4ab2159806bf6c99a98999502ee Message-Id: <20220929033854.7995F3858D1E@sourceware.org> Date: Thu, 29 Sep 2022 03:38:54 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b0969fa53a28b4ab2159806bf6c99a98999502ee commit b0969fa53a28b4ab2159806bf6c99a98999502ee Author: Noah Goldstein Date: Tue Sep 20 17:58:04 2022 -0700 x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591] 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. Diff: --- 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