[PATCH] D39206: [libunwind] Add missing checks for register number

[Martin Storsjö via Phabricator via cfe-commits]

mstorsjo created this revision.
Herald added a subscriber: JDevlieghere.

Most other cases that touch `savedRegisters[reg]` have got this check, but these three seemed to lack it.


https://reviews.llvm.org/D39206

Files:
  src/DwarfParser.hpp


Index: src/DwarfParser.hpp
===================================================================
--- src/DwarfParser.hpp
+++ src/DwarfParser.hpp
@@ -605,6 +605,11 @@
       break;
     case DW_CFA_val_offset:
       reg = addressSpace.getULEB128(p, instructionsEnd);
+      if (reg > kMaxRegisterNumber) {
+        fprintf(stderr,
+                "malformed DW_CFA_val_offset DWARF unwind, reg too big\n");
+        return false;
+      }
       offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
                                                     * cieInfo.dataAlignFactor;
       results->savedRegisters[reg].location = kRegisterOffsetFromCFA;
@@ -668,6 +673,11 @@
       switch (opcode & 0xC0) {
       case DW_CFA_offset:
         reg = operand;
+        if (reg > kMaxRegisterNumber) {
+          fprintf(stderr,
+                  "malformed DW_CFA_offset DWARF unwind, reg too big\n");
+          return false;
+        }
         offset = (int64_t)addressSpace.getULEB128(p, instructionsEnd)
                                                     * cieInfo.dataAlignFactor;
         results->savedRegisters[reg].location = kRegisterInCFA;
@@ -682,6 +692,11 @@
         break;
       case DW_CFA_restore:
         reg = operand;
+        if (reg > kMaxRegisterNumber) {
+          fprintf(stderr,
+                  "malformed DW_CFA_restore DWARF unwind, reg too big\n");
+          return false;
+        }
         results->savedRegisters[reg] = initialState.savedRegisters[reg];
         _LIBUNWIND_TRACE_DWARF("DW_CFA_restore(reg=%" PRIu64 ")\n",
                                static_cast<uint64_t>(operand));


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