[Bug libdw/28654] New: There seems to be an infinite loop somewhere in dwfl_segment_report_module

[Bug libdw/28654] New: There seems to be an infinite loop somewhere in dwfl_segment_report_module

[evvers at ya dot ru]

https://sourceware.org/bugzilla/show_bug.cgi?id=28654

            Bug ID: 28654
           Summary: There seems to be an infinite loop somewhere in
                    dwfl_segment_report_module
           Product: elfutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libdw
          Assignee: unassigned at sourceware dot org
          Reporter: evvers at ya dot ru
                CC: elfutils-devel at sourceware dot org
  Target Milestone: ---

Created attachment 13822
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13822&action=edit
file triggering an infinite loop in dwfl_segment_report_module

One of systemd fuzz targets discovered what seems to be an infinite loop in
dwfl_segment_report_module. It can be reproduced by building the master branch
of the elfutils repository and passing the attachment to `./src/stack`:
```
$ git describe
elfutils-0.186-7-g99782bd2
```
```
autoreconf -i -f
./configure --enable-maintainer-mode
make -j$(nproc) V=1
LD_PRELOAD="./libelf/libelf.so ./libdw/libdw.so" ./src/stack --core
oss-fuzz-41572
```

According to `eu-stack` it's in dwfl_segment_report_module
```
#0  0x00007fa48b3eecf3 dwfl_segment_report_module
#1  0x00007fa48b3f2c88 dwfl_core_file_report@@ELFUTILS_0.158
#2  0x0000000000402ec7 parse_opt
#3  0x00007fa48b0abf82 argp_parse
#4  0x00000000004024eb main
#5  0x00007fa48afc6b75 __libc_start_main
#6  0x000000000040272e _start
```

It was also reported in
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=41572
```
ALARM: working on the last Unit for 61 seconds
       and the timeout value is 60 (use -timeout=N to change)
==782== ERROR: libFuzzer: timeout after 61 seconds
    #0 0x52fdb1 in __sanitizer_print_stack_trace
/src/llvm-project/compiler-rt/lib/asan/asan_stack.cpp:87:3
    #1 0x4707e8 in fuzzer::PrintStackTrace() cxa_noexception.cpp:0
    #2 0x455679 in fuzzer::Fuzzer::AlarmCallback() cxa_noexception.cpp:0
    #3 0x7ff8fd7473bf in libpthread.so.0
    #4 0x46e23c in HandleCmp<unsigned long>
/src/llvm-project/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp:390:31
    #5 0x46e23c in __sanitizer_cov_trace_cmp8
/src/llvm-project/compiler-rt/lib/fuzzer/FuzzerTracePC.cpp:483:15
    #6 0x5f6edb in dwfl_segment_report_module
/src/elfutils/libdwfl/dwfl_segment_report_module.c:546:29
    #7 0x567135 in dwfl_core_file_report
/src/elfutils/libdwfl/core-file.c:559:17
    #8 0x55f280 in LLVMFuzzerTestOneInput /src/fuzz-dwfl-core.c:52:6
    #9 0x456ca3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*,
unsigned long) cxa_noexception.cpp:0
    #10 0x4425b2 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned
long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:324:6
    #11 0x44807a in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char
const*, unsigned long)) cxa_noexception.cpp:0
    #12 0x470fa2 in main
/src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10
    #13 0x7ff8fd53b0b2 in __libc_start_main
/build/glibc-eX1tMB/glibc-2.31/csu/libc-start.c:308:16
    #14 0x41f83d in _start
SUMMARY: libFuzzer: timeout
```

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug libdw/28654] There seems to be an infinite loop somewhere in dwfl_segment_report_module

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28654

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-12-08
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
           Assignee|unassigned at sourceware dot org   |mark at klomp dot org
                 CC|                            |mark at klomp dot org

--- Comment #1 from Mark Wielaard <mark at klomp dot org> ---
Proposed fix:
https://sourceware.org/pipermail/elfutils-devel/2021q4/004463.html

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug libdw/28654] There seems to be an infinite loop somewhere in dwfl_segment_report_module

[evvers at ya dot ru]

https://sourceware.org/bugzilla/show_bug.cgi?id=28654

--- Comment #2 from Evgeny Vereshchagin <evvers at ya dot ru> ---
I applied the patch on top of the master branch with the other two patches
related to libwfl applied and ran `src/stack` under Valgrind. I also ran the
unit tests on four different architectures just in case and they all passed
there. Looks like the issue is gone. Thanks!

-- 
You are receiving this mail because:
You are on the CC list for the bug.

[Bug libdw/28654] There seems to be an infinite loop somewhere in dwfl_segment_report_module

[mark at klomp dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28654

Mark Wielaard <mark at klomp dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #3 from Mark Wielaard <mark at klomp dot org> ---
Thanks for testing. Pushed as:

commit 9098a37fcfb67342ad955efc71d1398e2f8a69c1
Author: Mark Wielaard <mark@klomp.org>
Date:   Wed Dec 8 18:02:27 2021 +0100

    libdwfl: Add overflow check while iterating in dwfl_segment_report_module

    While iterating the notes we could overflow the len variable if the
    note name or description was too big. Fix this by adding an (unsigned)
    overflow check.

    https://sourceware.org/bugzilla/show_bug.cgi?id=28654

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

-- 
You are receiving this mail because:
You are on the CC list for the bug.