From daf4ef50c88c2b9a6bf2c40b537eebc202caad6e Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?S=C3=A9bastien=20Gonzalve?=

 <sebastien.gonzalve@aliceadsl.fr>

Date: Sat, 14 Nov 2020 10:39:47 +0100

Subject: [PATCH] Do not try to access element when vector is empty

Trying to access tmp[0] causes a crash on Fedora when assertion on STL

are enabled.

/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.

This patch just passes nullptr as pointer to getSortKey() when tmp size

is 0, preventing dereferencing elements in empty vector.

I guess that &tmp[0] should be optimized as 'no real access' when

disabling assertion, but actually leads to crash when assert are

enabled.

---

 src/icu/collator.cpp | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libs/locale/src/icu/collator.cpp b/libs/locale/src/icu/collator.cpp

index 7f1ea6a..dc59e8c 100644

--- a/libs/locale/src/icu/collator.cpp

+++ b/libs/locale/src/icu/collator.cpp

@@ -93,7 +93,7 @@ namespace boost {

                     std::vector<uint8_t> tmp;

                     tmp.resize(str.length());

                     icu::Collator *collate = get_collator(level);

-                    int len = collate->getSortKey(str,&tmp[0],tmp.size());

+                    int len = collate->getSortKey(str,tmp.empty()?nullptr:&tmp[0],tmp.size());

                     if(len > int(tmp.size())) {

                         tmp.resize(len);

                         collate->getSortKey(str,&tmp[0],tmp.size());

-- 

2.26.2