llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-lldb Author: Daniil Kovalev (kovdan01) <details> <summary>Changes</summary> If `LLVM_TARGETS_TO_BUILD` does not contain `X86` and we try to run an x86 binary in lldb, we get a `nullptr` dereference in `LLVMDisasmInstruction(...)`. We try to call `getDisAsm()` method on a `LLVMDisasmContext *DC` which is null. The pointer is passed from `x86AssemblyInspectionEngine::instruction_length(...)` and is originally `m_disasm_context` member of `x86AssemblyInspectionEngine`. This should be filled by `LLVMCreateDisasm(...)` in the class constructor, but not having X86 target enabled in llvm makes `TargetRegistry::lookupTarget(...)` call return `nullptr`, which results in `m_disasm_context` initialized with `nullptr` as well. This patch adds if statements against `m_disasm_context` in `x86AssemblyInspectionEngine::GetNonCallSiteUnwindPlanFromAssembly(...)` and `x86AssemblyInspectionEngine::FindFirstNonPrologueInstruction(...)` so subsequent calls to `x86AssemblyInspectionEngine::instruction_length(...)` do not cause a null pointer dereference. --- Full diff: https://github.com/llvm/llvm-project/pull/82603.diff 1 Files Affected: - (modified) lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp (+6) ``````````diff diff --git a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp index 2032c5a68d054c..6bfaa54135a959 100644 --- a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp +++ b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp @@ -909,6 +909,9 @@ bool x86AssemblyInspectionEngine::GetNonCallSiteUnwindPlanFromAssembly( if (!m_register_map_initialized) return false; + if (m_disasm_context == nullptr) + return false; + addr_t current_func_text_offset = 0; int current_sp_bytes_offset_from_fa = 0; bool is_aligned = false; @@ -1570,6 +1573,9 @@ bool x86AssemblyInspectionEngine::FindFirstNonPrologueInstruction( if (!m_register_map_initialized) return false; + if (m_disasm_context == nullptr) + return false; + while (offset < size) { int regno; int insn_len; `````````` </details> https://github.com/llvm/llvm-project/pull/82603 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
