[Bug binutils/29848] New: Out-of-bound read in function `parse_module`

[r3tr0spect2019 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29848

            Bug ID: 29848
           Summary: Out-of-bound read in function `parse_module`
           Product: binutils
           Version: 2.40 (HEAD)
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: r3tr0spect2019 at gmail dot com
  Target Milestone: ---

Created attachment 14479
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14479&action=edit
PoC

# Reproduce

cd binutils-gdb
git reset --hard aaa8dbc1b31233f66131476e03ab8635805e515d
mkdir build && cd build
../configure --disable-gdb --disable-gdbserver --disable-gdbsupport
--disable-libdecnumber --disable-readline --disable-sim --disable-libbacktrace
--disable-gas --disable-ld --disable-werror --enable-targets=all
CPPFLAGS=-DDEBUG CFLAGS="-g -O0 -fsanitize=address"
make all-binutils MAKEINFO=true && true
echo "" | binutils/addr2line -e ../parse_module_oob.bin

# Output

=================================================================
==72973==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x6020000000d3 at pc 0x5650a12e7550 bp 0x7ffcaa77e260 sp 0x7ffcaa77e250
READ of size 1 at 0x6020000000d3 thread T0
    #0 0x5650a12e754f in bfd_getl16 ../../bfd/libbfd.c:633
    #1 0x5650a18a6f11 in parse_module ../../bfd/vms-alpha.c:4373
    #2 0x5650a18a8fb7 in module_find_nearest_line ../../bfd/vms-alpha.c:4902
    #3 0x5650a18a991b in _bfd_vms_find_nearest_line ../../bfd/vms-alpha.c:4982
    #4 0x5650a12ceb1e in find_address_in_section ../../binutils/addr2line.c:197
    #5 0x5650a12f09fc in bfd_map_over_sections ../../bfd/section.c:1374
    #6 0x5650a12cf8eb in translate_addresses ../../binutils/addr2line.c:337
    #7 0x5650a12cffbc in process_file ../../binutils/addr2line.c:470
    #8 0x5650a12d05b1 in main ../../binutils/addr2line.c:579
    #9 0x7f9adfaf7d8f in __libc_start_call_main
../sysdeps/nptl/libc_start_call_main.h:58
    #10 0x7f9adfaf7e3f in __libc_start_main_impl ../csu/libc-start.c:392
    #11 0x5650a12ce244 in _start
(/binutils-gdb/build/binutils/addr2line+0x343244)

0x6020000000d3 is located 1 bytes to the right of 2-byte region
[0x6020000000d0,0x6020000000d2)
allocated by thread T0 here:
    #0 0x7f9adfdaa867 in __interceptor_malloc
../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x5650a12e71d7 in bfd_malloc ../../bfd/libbfd.c:289
    #2 0x5650a1892148 in _bfd_malloc_and_read ../../bfd/libbfd.h:970
    #3 0x5650a18a8f81 in module_find_nearest_line ../../bfd/vms-alpha.c:4896
    #4 0x5650a18a991b in _bfd_vms_find_nearest_line ../../bfd/vms-alpha.c:4982
    #5 0x5650a12ceb1e in find_address_in_section ../../binutils/addr2line.c:197
    #6 0x5650a12f09fc in bfd_map_over_sections ../../bfd/section.c:1374
    #7 0x5650a12cf8eb in translate_addresses ../../binutils/addr2line.c:337
    #8 0x5650a12cffbc in process_file ../../binutils/addr2line.c:470
    #9 0x5650a12d05b1 in main ../../binutils/addr2line.c:579
    #10 0x7f9adfaf7d8f in __libc_start_call_main
../sysdeps/nptl/libc_start_call_main.h:58

SUMMARY: AddressSanitizer: heap-buffer-overflow ../../bfd/libbfd.c:633 in
bfd_getl16
Shadow bytes around the buggy address:
  0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff8000: fa fa fd fa fa fa 00 04 fa fa 00 04 fa fa 00 04
=>0x0c047fff8010: fa fa 00 01 fa fa fd fd fa fa[02]fa fa fa fa fa
  0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8060: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==72973==ABORTING
Aborted (core dumped)

# Analysis

Function call `bfd_getl16 (ptr + 2)` can access byte `ptr[3]`, but the check
`ptr < maxptr` only ensures that `ptr[0]` is accessible, which causes the
out-of-bound read.[1]

[1]
https://github.com/bminor/binutils-gdb/blob/aaa8dbc1b31233f66131476e03ab8635805e515d/bfd/vms-alpha.c#L4373

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