82 lines
2.8 KiB
Diff
82 lines
2.8 KiB
Diff
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From 1a8db070fa42276f290e20c294a51b4fc9c51f83 Mon Sep 17 00:00:00 2001
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From: Florian Weimer <fweimer@redhat.com>
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Date: Sat, 15 Dec 2018 18:58:09 +0100
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Subject: [PATCH 61] support: Do not require overflow builtin in
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support/blob_repeat.c
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It is only available in GCC 5 and later.
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Tested-by: Romain Naour <romain.naour@gmail.com>
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(cherry picked from commit 0c1719e65b2a5a80331d4f635612799f853b0479)
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---
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ChangeLog | 6 ++++++
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support/blob_repeat.c | 26 +++++++++++++++++++++++---
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2 files changed, 29 insertions(+), 3 deletions(-)
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diff --git a/ChangeLog b/ChangeLog
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index c12b5995a3..d8459496ba 100644
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--- a/ChangeLog
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+++ b/ChangeLog
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@@ -1,3 +1,9 @@
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+2018-12-15 Florian Weimer <fweimer@redhat.com>
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+
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+ * support/blob_repeat.c (check_mul_overflow_size_t): New function.
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+ (minimum_stride_size): Use it.
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+ (support_blob_repeat_allocate): Likewise.
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+
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2018-12-13 Andreas Schwab <schwab@suse.de>
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[BZ #23861]
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diff --git a/support/blob_repeat.c b/support/blob_repeat.c
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index 16c1e448b9..718846d81d 100644
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--- a/support/blob_repeat.c
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+++ b/support/blob_repeat.c
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@@ -34,6 +34,26 @@
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optimization because mappings carry a lot of overhead. */
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static const size_t maximum_small_size = 4 * 1024 * 1024;
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+/* Set *RESULT to LEFT * RIGHT. Return true if the multiplication
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+ overflowed. See <malloc/malloc-internal.h>. */
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+static inline bool
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+check_mul_overflow_size_t (size_t left, size_t right, size_t *result)
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+{
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+#if __GNUC__ >= 5
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+ return __builtin_mul_overflow (left, right, result);
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+#else
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+ /* size_t is unsigned so the behavior on overflow is defined. */
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+ *result = left * right;
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+ size_t half_size_t = ((size_t) 1) << (8 * sizeof (size_t) / 2);
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+ if (__glibc_unlikely ((left | right) >= half_size_t))
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+ {
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+ if (__glibc_unlikely (right != 0 && *result / right != left))
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+ return true;
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+ }
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+ return false;
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+#endif
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+}
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+
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/* Internal helper for fill. */
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static void
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fill0 (char *target, const char *element, size_t element_size,
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@@ -118,8 +138,8 @@ minimum_stride_size (size_t page_size, size_t element_size)
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common multiple, it appears only once. Therefore, shift one
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factor. */
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size_t multiple;
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- if (__builtin_mul_overflow (page_size >> common_zeros, element_size,
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- &multiple))
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+ if (check_mul_overflow_size_t (page_size >> common_zeros, element_size,
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+ &multiple))
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return 0;
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return multiple;
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}
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@@ -255,7 +275,7 @@ support_blob_repeat_allocate (const void *element, size_t element_size,
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size_t count)
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{
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size_t total_size;
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- if (__builtin_mul_overflow (element_size, count, &total_size))
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+ if (check_mul_overflow_size_t (element_size, count, &total_size))
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{
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errno = EOVERFLOW;
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return (struct support_blob_repeat) { 0 };
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