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From daf4ef50c88c2b9a6bf2c40b537eebc202caad6e Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?S=C3=A9bastien=20Gonzalve?=
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 <sebastien.gonzalve@aliceadsl.fr>
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Date: Sat, 14 Nov 2020 10:39:47 +0100
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Subject: [PATCH] Do not try to access element when vector is empty
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Trying to access tmp[0] causes a crash on Fedora when assertion on STL
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are enabled.
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/usr/include/c++/10/bits/stl_vector.h:1045: std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](std::vector<_Tp, _Alloc>::size_type) [with _Tp = unsigned char; _Alloc = std::allocator<unsigned char>; std::vector<_Tp, _Alloc>::reference = unsigned char&; std::vector<_Tp, _Alloc>::size_type = long unsigned int]: Assertion '__builtin_expect(__n < this->size(), true)' failed.
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This patch just passes nullptr as pointer to getSortKey() when tmp size
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is 0, preventing dereferencing elements in empty vector.
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I guess that &tmp[0] should be optimized as 'no real access' when
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disabling assertion, but actually leads to crash when assert are
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enabled.
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---
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 src/icu/collator.cpp | 2 +-
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 1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/libs/locale/src/icu/collator.cpp b/libs/locale/src/icu/collator.cpp
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index 7f1ea6a..dc59e8c 100644
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--- a/libs/locale/src/icu/collator.cpp
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+++ b/libs/locale/src/icu/collator.cpp
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@@ -93,7 +93,7 @@ namespace boost {
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                     std::vector<uint8_t> tmp;
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                     tmp.resize(str.length());
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                     icu::Collator *collate = get_collator(level);
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-                    int len = collate->getSortKey(str,&tmp[0],tmp.size());
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+                    int len = collate->getSortKey(str,tmp.empty()?nullptr:&tmp[0],tmp.size());
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                     if(len > int(tmp.size())) {
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                         tmp.resize(len);
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                         collate->getSortKey(str,&tmp[0],tmp.size());
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-- 
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2.26.2
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