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authorJulian Andres Klode <julian.klode@canonical.com>2020-02-25 11:26:18 +0100
committerJulian Andres Klode <julian.klode@canonical.com>2020-02-25 11:27:30 +0100
commitf17e3ce8213ba364d1eea7b5bab286a2175e5875 (patch)
tree1542a2cc1c8315aaa38e37c16ca17bac94985ac9 /apt-pkg
parent4fad7262291a8af1415fb9a3693678bd9610f0d6 (diff)
Silence narrow conversion warnings, add error checks
When converting a long offset to a uint32_t to be stored in the map, check that this is safe to do. If the offset is negative, or we lose data in the conversion, we lost.
Diffstat (limited to 'apt-pkg')
-rw-r--r--apt-pkg/pkgcachegen.cc27
1 files changed, 20 insertions, 7 deletions
diff --git a/apt-pkg/pkgcachegen.cc b/apt-pkg/pkgcachegen.cc
index 83a8c2e63..283866f88 100644
--- a/apt-pkg/pkgcachegen.cc
+++ b/apt-pkg/pkgcachegen.cc
@@ -48,6 +48,19 @@ static bool IsDuplicateDescription(pkgCache &Cache, pkgCache::DescIterator Desc,
using std::string;
using APT::StringView;
+// Convert an offset returned from e.g. DynamicMMap or ptr difference to
+// an uint32_t location without data loss.
+template <typename T>
+static inline uint32_t NarrowOffset(T ptr)
+{
+ uint32_t res = static_cast<uint32_t>(ptr);
+ if (unlikely(ptr < 0))
+ abort();
+ if (unlikely(static_cast<T>(res) != ptr))
+ abort();
+ return res;
+}
+
// CacheGenerator::pkgCacheGenerator - Constructor /*{{{*/
// ---------------------------------------------------------------------
/* We set the dirty flag and make sure that is written to the disk */
@@ -210,7 +223,7 @@ map_stringitem_t pkgCacheGenerator::WriteStringInMap(const char *String,
const unsigned long &Len) {
size_t oldSize = Map.Size();
void const * const oldMap = Map.Data();
- map_stringitem_t const index{Map.WriteString(String, Len)};
+ map_stringitem_t const index{NarrowOffset(Map.WriteString(String, Len))};
if (index != 0)
ReMap(oldMap, Map.Data(), oldSize);
return index;
@@ -220,7 +233,7 @@ map_stringitem_t pkgCacheGenerator::WriteStringInMap(const char *String,
map_stringitem_t pkgCacheGenerator::WriteStringInMap(const char *String) {
size_t oldSize = Map.Size();
void const * const oldMap = Map.Data();
- map_stringitem_t const index{Map.WriteString(String)};
+ map_stringitem_t const index{NarrowOffset(Map.WriteString(String))};
if (index != 0)
ReMap(oldMap, Map.Data(), oldSize);
return index;
@@ -827,7 +840,7 @@ bool pkgCacheGenerator::NewFileVer(pkgCache::VerIterator &Ver,
return false;
pkgCache::VerFileIterator VF(Cache,Cache.VerFileP + VerFile);
- VF->File = map_pointer<pkgCache::PackageFile>{CurrentFile - Cache.PkgFileP};
+ VF->File = map_pointer<pkgCache::PackageFile>{NarrowOffset(CurrentFile - Cache.PkgFileP)};
// Link it to the end of the list
map_pointer<pkgCache::VerFile> *Last = &Ver->FileList;
@@ -912,7 +925,7 @@ bool pkgCacheGenerator::NewFileDesc(pkgCache::DescIterator &Desc,
return false;
pkgCache::DescFileIterator DF(Cache,Cache.DescFileP + DescFile);
- DF->File = map_pointer<pkgCache::PackageFile>{CurrentFile - Cache.PkgFileP};
+ DF->File = map_pointer<pkgCache::PackageFile>{NarrowOffset(CurrentFile - Cache.PkgFileP)};
// Link it to the end of the list
map_pointer<pkgCache::DescFile> *Last = &Desc->FileList;
@@ -1267,7 +1280,7 @@ bool pkgCacheGenerator::SelectReleaseFile(const string &File,const string &Site,
CurrentRlsFile->Flags = Flags;
CurrentRlsFile->ID = Cache.HeaderP->ReleaseFileCount;
RlsFileName = File;
- Cache.HeaderP->RlsFileList = map_pointer<pkgCache::ReleaseFile>{CurrentRlsFile - Cache.RlsFileP};
+ Cache.HeaderP->RlsFileList = map_pointer<pkgCache::ReleaseFile>{NarrowOffset(CurrentRlsFile - Cache.RlsFileP)};
Cache.HeaderP->ReleaseFileCount++;
return true;
@@ -1316,11 +1329,11 @@ bool pkgCacheGenerator::SelectFile(std::string const &File,
CurrentFile->Component = component;
CurrentFile->Flags = Flags;
if (CurrentRlsFile != nullptr)
- CurrentFile->Release = map_pointer<pkgCache::ReleaseFile>{CurrentRlsFile - Cache.RlsFileP};
+ CurrentFile->Release = map_pointer<pkgCache::ReleaseFile>{NarrowOffset(CurrentRlsFile - Cache.RlsFileP)};
else
CurrentFile->Release = 0;
PkgFileName = File;
- Cache.HeaderP->FileList = map_pointer<pkgCache::PackageFile>{CurrentFile - Cache.PkgFileP};
+ Cache.HeaderP->FileList = map_pointer<pkgCache::PackageFile>{NarrowOffset(CurrentFile - Cache.PkgFileP)};
Cache.HeaderP->PackageFileCount++;
if (Progress != 0)