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[MachO] Prevent heap overflow when load command extends past EOF

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This patch fixes a heap-buffer-overflow when a malformed Mach-O has a
load command who's size extends past the end of the binary.

Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3225

Differential revision: https://reviews.llvm.org/D37439

llvm-svn: 313145
This commit is contained in:
Jonas Devlieghere
2017-09-13 13:43:01 +00:00
parent 35f4d7ca46
commit 81f5abe1ad
3 changed files with 7 additions and 1 deletions
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5
llvm/lib/Object/MachOObjectFile.cpp
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@@ -183,6 +183,9 @@ static Expected<MachOObjectFile::LoadCommandInfo>
getLoadCommandInfo(const MachOObjectFile &Obj, const char *Ptr,
uint32_t LoadCommandIndex) {
if (auto CmdOrErr = getStructOrErr<MachO::load_command>(Obj, Ptr)) {
if (CmdOrErr->cmdsize + Ptr > Obj.getData().end())
return malformedError("load command " + Twine(LoadCommandIndex) +
" extends past end of file");
if (CmdOrErr->cmdsize < 8)
return malformedError("load command " + Twine(LoadCommandIndex) +
" with size less than 8 bytes");
@@ -800,7 +803,7 @@ static Error checkNoteCommand(const MachOObjectFile &Obj,
uint32_t LoadCommandIndex,
std::list<MachOElement> &Elements) {
if (Load.C.cmdsize != sizeof(MachO::note_command))
return malformedError("load command " + Twine(LoadCommandIndex) +
return malformedError("load command " + Twine(LoadCommandIndex) +
" LC_NOTE has incorrect cmdsize");
MachO::note_command Nt = getStruct<MachO::note_command>(Obj, Load.Ptr);
uint64_t FileSize = Obj.getData().size();