[Bug tools/24116] New: A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[Bug tools/24116] New: A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[wcventure at 126 dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

            Bug ID: 24116
           Summary: A Heap-buffer-overflow problem was discovered in the
                    function print_debug_line_section in readelf.c
           Product: elfutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tools
          Assignee: unassigned at sourceware dot org
          Reporter: wcventure at 126 dot com
                CC: elfutils-devel at sourceware dot org
  Target Milestone: ---

Created attachment 11559
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11559&action=edit
POC1

Hi, 

A Heap-buffer-overflow problem was discovered in the function
print_debug_line_section in readelf.c, as distributed in ELFutils 0.175. A
crafted ELF input can cause segment faults and I have confirmed them with
address sanitizer too.

Here are the POC files. Please use "./eu-readelf -w $POC" to reproduce the
error.

$git log

> commit de01cc6f9446187d69b9748bb3636361c79e77a4
> Author: Mark Wielaard <mark@klomp.org>
> Date:   Wed Jan 16 15:41:31 2019 +0100
> 
>     libebl: Check NT_PLATFORM core notes contain a zero terminated string.
> 
>     Most strings in core notes are fixed size. But NT_PLATFORM contains just
>     a variable length string. Check that it is actually zero terminated
>     before passing to readelf to print.
> 
>     https://sourceware.org/bugzilla/show_bug.cgi?id=24089
> 
>     Signed-off-by: Mark Wielaard <mark@klomp.org>

The ASAN dumps the stack trace as follows:

> =================================================================
> ==23533==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6100000002fc at pc 0x00000040507c bp 0x7ffd4aa3fa10 sp 0x7ffd4aa3fa00
> READ of size 1 at 0x6100000002fc thread T0
>     #0 0x40507b in __libdw_get_uleb128 ../libdw/memory-access.h:80
>     #1 0x496de9 in print_debug_line_section /elfutils/src/readelf.c:8846
>     #2 0x45be8c in print_debug /elfutils/src/readelf.c:11207
>     #3 0x46080a in process_elf_file /elfutils/src/readelf.c:998
>     #4 0x46080a in process_dwflmod /elfutils/src/readelf.c:760
>     #5 0x7f38d437171c in dwfl_getmodules /elfutils/libdwfl/dwfl_getmodules.c:86
>     #6 0x40cb1d in process_file /elfutils/src/readelf.c:868
>     #7 0x4059a6 in main /elfutils/src/readelf.c:350
>     #8 0x7f38d39f782f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
>     #9 0x4064d8 in _start (/elfutils/build/bin/eu-readelf+0x4064d8)
> 
> 0x6100000002fc is located 0 bytes to the right of 188-byte region [0x610000000240,0x6100000002fc)
> allocated by thread T0 here:
>     #0 0x7f38d474eb90 in __interceptor_malloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xdeb90)
>     #1 0x7f38d4003f7f in convert_data /elfutils/libelf/elf_getdata.c:157
>     #2 0x7f38d4003f7f in __libelf_set_data_list_rdlock /elfutils/libelf/elf_getdata.c:447
> 
> SUMMARY: AddressSanitizer: heap-buffer-overflow ../libdw/memory-access.h:80 in __libdw_get_uleb128
> Shadow bytes around the buggy address:
>   0x0c207fff8000: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
>   0x0c207fff8010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x0c207fff8020: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
>   0x0c207fff8030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x0c207fff8040: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
> =>0x0c207fff8050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00[04]
>   0x0c207fff8060: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
>   0x0c207fff8070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>   0x0c207fff8080: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>   0x0c207fff8090: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>   0x0c207fff80a0: 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
> ==23533==ABORTING

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[wcventure at 126 dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

--- Comment #2 from wcventure <wcventure at 126 dot com> ---
Created attachment 11561
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11561&action=edit
POC3

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[wcventure at 126 dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

--- Comment #1 from wcventure <wcventure at 126 dot com> ---
Created attachment 11560
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11560&action=edit
POC2

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |mark at klomp dot org
         Resolution|---                         |FIXED

--- Comment #3 from Mark Wielaard <mark at klomp dot org> ---
Yeah, we should check the unknown parameters are actually there.
Luckily other checks make sure we don't read more than one byte past the end of
the data.

commit a17c2c0917901ffa542ac4d3e327d46742219e04
Author: Mark Wielaard <mark@klomp.org>
Date:   Tue Jan 22 15:55:18 2019 +0100

    readelf: Don't go past end of line data reading unknown opcode parameters.

    https://sourceware.org/bugzilla/show_bug.cgi?id=24116

    Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/src/readelf.c b/src/readelf.c
index 6bad3bf..e3e699c 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -8845,7 +8845,8 @@ print_debug_line_section (Dwfl_Module *dwflmod, Ebl *ebl,
GElf_Ehdr *ehdr,
                                " unknown opcode with %" PRIu8 " parameters:",
                                standard_opcode_lengths[opcode]),
                      standard_opcode_lengths[opcode]);
-             for (int n = standard_opcode_lengths[opcode]; n > 0; --n)
+             for (int n = standard_opcode_lengths[opcode];
+                  n > 0 && linep < lineendp; --n)
                {
                  get_uleb128 (u128, linep, lineendp);
                  if (n != standard_opcode_lengths[opcode])

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[wcventure at 126 dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

--- Comment #4 from wcventure <wcventure at 126 dot com> ---
(In reply to Mark Wielaard from comment #3)

Not completely repaired.
Here is the Regression test case.

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[wcventure at 126 dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

--- Comment #5 from wcventure <wcventure at 126 dot com> ---
Created attachment 11581
  --> https://sourceware.org/bugzilla/attachment.cgi?id=11581&action=edit
Regression

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[Bug tools/24116] A Heap-buffer-overflow problem was discovered in the function print_debug_line_section in readelf.c

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=24116

--- Comment #6 from Mark Wielaard <mark at klomp dot org> ---
(In reply to wcventure from comment #5)
> Created attachment 11581 [details]
> Regression

Running with:
 valgrind -q src/readelf --debug-dump=line ./RegressionPOC
will produce:

==57142== Invalid read of size 2
==57142==    at 0x12F431: print_debug_line_section (readelf.c:8807)
==57142==    by 0x11E2C0: print_debug (readelf.c:11212)
==57142==    by 0x1201C0: process_elf_file (readelf.c:998)
==57142==    by 0x1201C0: process_dwflmod (readelf.c:760)
==57142==    by 0x486D6A0: dwfl_getmodules (dwfl_getmodules.c:86)
==57142==    by 0x11414F: process_file (readelf.c:868)
==57142==    by 0x111C33: main (readelf.c:350)
==57142==  Address 0x4f20a83 is 0 bytes after a block of size 339 alloc'd
==57142==    at 0x483577F: malloc (vg_replace_malloc.c:299)
==57142==    by 0x48A0358: convert_data (elf_getdata.c:157)
==57142==    by 0x48A0358: __libelf_set_data_list_rdlock (elf_getdata.c:447)
==57142==    by 0x48A0547: __elf_getdata_rdlock (elf_getdata.c:554)
==57142==    by 0x484EFB0: check_section (dwarf_begin_elf.c:167)
==57142==    by 0x484F522: global_read (dwarf_begin_elf.c:310)
==57142==    by 0x484F522: dwarf_begin_elf (dwarf_begin_elf.c:445)
==57142==    by 0x486F9A7: load_dw (dwfl_module_getdwarf.c:1342)
==57142==    by 0x486FBCB: find_dw (dwfl_module_getdwarf.c:1392)
==57142==    by 0x486FBCB: dwfl_module_getdwarf (dwfl_module_getdwarf.c:1447)
==57142==    by 0x11DD4A: print_debug (readelf.c:10943)
==57142==    by 0x1201C0: process_elf_file (readelf.c:998)
==57142==    by 0x1201C0: process_dwflmod (readelf.c:760)
==57142==    by 0x486D6A0: dwfl_getmodules (dwfl_getmodules.c:86)
==57142==    by 0x11414F: process_file (readelf.c:868)
==57142==    by 0x111C33: main (readelf.c:350)
==57142== 

Fixed by:

commit cad9595592730fd8c9d0d9236d38f62ec8cfbcef
Author: Mark Wielaard <mark@klomp.org>
Date:   Fri Feb 1 09:08:14 2019 +0100

    readelf: Check there is enough data to read DWARF line opcodes arguments.

    When reading the debug_line opcode arguments we have to make sure there
    is enough data to read the arguments (if there are any(.

    The similar code in dwarf_getsrclines already had these checks.

    https://sourceware.org/bugzilla/show_bug.cgi?id=24116

    Signed-off-by: Mark Wielaard <mark@klomp.org>

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