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Kernel+LibELF: Don't blindly trust ELF symbol offsets in symbolication

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It was possible to craft a custom ELF executable that when symbolicated
would cause the kernel to read from user-controlled addresses anywhere
in memory. You could then fetch this memory via /proc/PID/stack

We fix this by making ELFImage hand out StringView rather than raw
const char* for symbol names. In case a symbol offset is outside the
ELF image, you get a null StringView. :^)

Test: Kernel/elf-symbolication-kernel-read-exploit.cpp
This commit is contained in:
Andreas Kling 2020-01-16 22:04:44 +01:00
parent 60143c8d4e
commit c6e552ac8f
9 changed files with 140 additions and 24 deletions
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2
Libraries/LibELF/ELFLoader.cpp
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@ -113,7 +113,7 @@ char* ELFLoader::symbol_ptr(const char* name)
m_image.for_each_symbol([&](const ELFImage::Symbol symbol) {
if (symbol.type() != STT_FUNC)
return IterationDecision::Continue;
if (strcmp(symbol.name(), name))
if (symbol.name() == name)
return IterationDecision::Continue;
if (m_image.is_executable())
found_ptr = (char*)(size_t)symbol.value();