129 lines
4.2 KiB
Diff
129 lines
4.2 KiB
Diff
commit e3255e7d2188d1731aad83ad0dc147513560aa1e
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Author: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Tue Sep 20 17:58:04 2022 -0700
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x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591]
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Previous implementation was adjusting length (rsi) to match
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bytes (eax), but since there is no bound to length this can cause
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overflow.
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Fix is to just convert the byte-count (eax) to length by dividing by
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sizeof (wchar_t) before the comparison.
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Full check passes on x86-64 and build succeeds w/ and w/o multiarch.
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(cherry picked from commit b0969fa53a28b4ab2159806bf6c99a98999502ee)
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diff --git a/string/test-strnlen.c b/string/test-strnlen.c
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index bb5d9b5f04fa6586..eac84cd17526d5d9 100644
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--- a/string/test-strnlen.c
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+++ b/string/test-strnlen.c
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@@ -75,7 +75,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
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{
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size_t i;
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- align &= 63;
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+ align &= (getpagesize () / sizeof (CHAR) - 1);
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if ((align + len) * sizeof (CHAR) >= page_size)
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return;
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@@ -92,36 +92,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
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static void
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do_overflow_tests (void)
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{
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- size_t i, j, len;
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+ size_t i, j, al_idx, repeats, len;
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const size_t one = 1;
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uintptr_t buf_addr = (uintptr_t) buf1;
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+ const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
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- for (i = 0; i < 750; ++i)
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+ for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
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+ al_idx++)
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{
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- do_test (0, i, SIZE_MAX - i, BIG_CHAR);
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- do_test (0, i, i - buf_addr, BIG_CHAR);
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- do_test (0, i, -buf_addr - i, BIG_CHAR);
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- do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
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- do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
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-
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- len = 0;
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- for (j = 8 * sizeof(size_t) - 1; j ; --j)
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- {
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- len |= one << j;
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- do_test (0, i, len - i, BIG_CHAR);
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- do_test (0, i, len + i, BIG_CHAR);
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- do_test (0, i, len - buf_addr - i, BIG_CHAR);
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- do_test (0, i, len - buf_addr + i, BIG_CHAR);
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-
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- do_test (0, i, ~len - i, BIG_CHAR);
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- do_test (0, i, ~len + i, BIG_CHAR);
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- do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
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- do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
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-
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- do_test (0, i, -buf_addr, BIG_CHAR);
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- do_test (0, i, j - buf_addr, BIG_CHAR);
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- do_test (0, i, -buf_addr - j, BIG_CHAR);
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- }
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+ for (repeats = 0; repeats < 2; ++repeats)
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+ {
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+ size_t align = repeats ? (getpagesize () - alignments[al_idx])
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+ : alignments[al_idx];
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+ align /= sizeof (CHAR);
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+ for (i = 0; i < 750; ++i)
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+ {
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+ do_test (align, i, SIZE_MAX, BIG_CHAR);
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+
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+ do_test (align, i, SIZE_MAX - i, BIG_CHAR);
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+ do_test (align, i, i - buf_addr, BIG_CHAR);
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+ do_test (align, i, -buf_addr - i, BIG_CHAR);
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+ do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
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+ do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
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+
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+ len = 0;
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+ for (j = 8 * sizeof (size_t) - 1; j; --j)
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+ {
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+ len |= one << j;
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+ do_test (align, i, len, BIG_CHAR);
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+ do_test (align, i, len - i, BIG_CHAR);
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+ do_test (align, i, len + i, BIG_CHAR);
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+ do_test (align, i, len - buf_addr - i, BIG_CHAR);
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+ do_test (align, i, len - buf_addr + i, BIG_CHAR);
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+
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+ do_test (align, i, ~len - i, BIG_CHAR);
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+ do_test (align, i, ~len + i, BIG_CHAR);
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+ do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
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+ do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
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+
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+ do_test (align, i, -buf_addr, BIG_CHAR);
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+ do_test (align, i, j - buf_addr, BIG_CHAR);
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+ do_test (align, i, -buf_addr - j, BIG_CHAR);
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+ }
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+ }
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+ }
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}
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}
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diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
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index b282a75613bf52ab..4d7d68396bcd4049 100644
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--- a/sysdeps/x86_64/multiarch/strlen-avx2.S
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+++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
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@@ -542,14 +542,11 @@ L(return_vzeroupper):
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L(cross_page_less_vec):
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tzcntl %eax, %eax
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# ifdef USE_AS_WCSLEN
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- /* NB: Multiply length by 4 to get byte count. */
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- sall $2, %esi
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+ /* NB: Divide by 4 to convert from byte-count to length. */
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+ shrl $2, %eax
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# endif
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cmpq %rax, %rsi
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cmovb %esi, %eax
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-# ifdef USE_AS_WCSLEN
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- shrl $2, %eax
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-# endif
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VZEROUPPER_RETURN
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# endif
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