Created attachment 249399 [details]
broken ELF file that causes an out-of-bounds read in llvm-objdump's printDynamicSection()

This code in llvm-project/llvm/tools/llvm-objdump/ELFDump.cpp
printDynamicSection() forms a pointer using Dyn.d_un_dval, which it
obtains from the ELF file, without a sanity check:

        const char *Data = StrTabOrErr.get().data();
        outs() << (Data + Dyn.d_un.d_val) << "\n";

I've attached a demonstration:

# uname -a
FreeBSD xxx 15.0-CURRENT FreeBSD 15.0-CURRENT #19 main-n268743-a58813fd701e: Sat Mar  9 07:18:21 AST 2024     root@xxx:/usr/obj/usr/src/amd64.amd64/sys/GENERIC amd64
# llvm-objdump --version
LLVM (http://llvm.org/):
  LLVM version 17.0.6
  Optimized build with assertions.
...
# llvm-objdump -x objdump10a.exe
...
Dynamic Section:
  NEEDED       PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace.
Stack dump:
0.      Program arguments: llvm-objdump -x objdump10a.exe
 #0 0x0000000001230c41 PrintStackTrace /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:602:13
 #1 0x000000000122f0b5 RunSignalHandlers /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:105:18
 #2 0x0000000001231365 SignalHandler /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3
 #3 0x00000008267d55ff handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
 #4 0x00000008267d4bbb thr_sighandler /usr/src/lib/libthr/thread/thr_sig.c:244:1
 #5 0x0000000822def2d3 ([vdso]+0x2d3)
 #6 0x0000000828b3a7eb /usr/src/lib/libc/amd64/string/strlen.S:95:0
 #7 0x0000000000df28c9 __constexpr_strlen /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__string/constexpr_c_functions.h:49:10
 #8 0x0000000000df28c9 length /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__string/char_traits.h:222:14
 #9 0x0000000000df28c9 StringRef /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/StringRef.h:90:33
#10 0x0000000000df28c9 operator<< /usr/src/contrib/llvm-project/llvm/include/llvm/Support/raw_ostream.h:244:29
#11 0x0000000000df28c9 printDynamicSection /usr/src/contrib/llvm-project/llvm/tools/llvm-objdump/ELFDump.cpp:233:16
#12 0x0000000000df28c9 printPrivateHeaders /usr/src/contrib/llvm-project/llvm/tools/llvm-objdump/ELFDump.cpp:431:3
#13 0x0000000000e6a13c dumpObject /usr/src/contrib/llvm-project/llvm/tools/llvm-objdump/llvm-objdump.cpp:2815:7
#14 0x0000000000e654b0 dumpInput /usr/src/contrib/llvm-project/llvm/tools/llvm-objdump/llvm-objdump.cpp:0:5
#15 0x0000000000e654b0 for_each<std::__1::__wrap_iter<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > *>, void (*)(llvm::StringRef)> /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/__algorithm/for_each.h:26:5
#16 0x0000000000e654b0 for_each<std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > &, void (*)(llvm::StringRef)> /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/STLExtras.h:1731:10
#17 0x0000000000e654b0 main /usr/src/contrib/llvm-project/llvm/tools/llvm-objdump/llvm-objdump.cpp:3248:3
#18 0x0000000828a660aa __libc_start1 /usr/src/lib/libc/csu/libc_start1.c:157:2
Segmentation fault (core dumped)