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Fix use-after-free when non-lazily processing corrupted sections #151

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Merged
serge1 merged 1 commit into from
Apr 12, 2025
Merged

Fix use-after-free when non-lazily processing corrupted sections #151

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3 changes: 3 additions & 0 deletions elfio/elfio.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,9 @@ class elfio

for ( Elf_Half i = 0; i < num; ++i ) {
section* sec = create_section();

// Load return value is ignored here
// This allows retrieval of information from corrupted sections
sec->load( stream,
static_cast<std::streamoff>( offset ) +
static_cast<std::streampos>( i ) * entry_size,
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16 changes: 13 additions & 3 deletions elfio/elfio_section.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -228,8 +228,16 @@ template <class T> class section_impl : public section
*/
const char* get_data() const override
{
if ( !is_loaded ) {
load_data();
// If data load failed, the stream is corrupt
// When lazy loading, attempts to call get_data() on it after initial load are useless
// When loading non-lazily, that load_data() will attempt to read data from
// the stream specified on load() call, which might be freed by this point
if ( !is_loaded && can_be_loaded ) {
bool res = load_data();

if ( !res ) {
can_be_loaded = false;
}
}
return data.get();
}
Expand Down Expand Up @@ -434,7 +442,7 @@ template <class T> class section_impl : public section
stream.read( reinterpret_cast<char*>( &header ), sizeof( header ) );

if ( !( is_lazy || is_loaded ) ) {
bool ret = load_data();
bool ret = get_data();

if ( is_compressed() ) {
Elf_Xword size = get_size();
Expand Down Expand Up @@ -588,6 +596,8 @@ template <class T> class section_impl : public section
false; /**< Flag indicating if lazy loading is enabled. */
mutable bool is_loaded =
false; /**< Flag indicating if the data is loaded. */
mutable bool can_be_loaded =
true; /**< Flag indicating if the data can loaded. This is not the case if the section is corrupted. */
};

} // namespace ELFIO
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