Project: libsass (sass/libsass), language: c++
Vulnerability instance: libsass.cve-2017-11556
Sanitizer: address

================= Bug Report (1/1) ==================
## Source: Red Hat Bugzilla
## URL: https://bugzilla.redhat.com/show_bug.cgi?id=1471786
## Description:
Bugzilla ID: 1471786
Title: There is a stack-overflow in the sassc of libsass library. This vulnerability is triggered in function Parser::advanceToNextToken() .

Description
owl337 2017-07-17 12:38:02 UTC
Created attachment 1299843 [details]
Triggered by "./sassc POC4"

Description of problem:

There is a stack-overflow in the sassc  of  libsass library. This vulnerability was triggered in function Parser::advanceToNextToken() at line /libsass/src/parser.cpp:66.

Version-Release number of selected component (if applicable):

<= latest version

How reproducible:

./sassc $POC

Steps to Reproduce:

The debugging information is as follows:

$ ./sassc POC4

Segmentation fault

ASAN debugging information:

$ ./sassc POC4
ASAN:SIGSEGV
=================================================================
==102693==ERROR: AddressSanitizer: stack-overflow on address 0x7fff6af5ac08 (pc 0x0000004a6f1d bp 0x7fff6af5b470 sp 0x7fff6af5ac10 T0)
    #0 0x4a6f1c  (/home/icy/secreal/sassc-asan/install/bin/sassc+0x4a6f1c)
    #1 0x7f45522d527d  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x46027d)
    #2 0x7f455229ec19  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x429c19)
    #3 0x7f45522d3cdc  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x45ecdc)
    #4 0x7f45522ce835  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x459835)
    #5 0x7f45522e393a  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x46e93a)
    #6 0x7f45522e1a81  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x46ca81)
    #7 0x7f45522d9611  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x464611)
    #8 0x7f45522d7e68  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x462e68)
    #9 0x7f45522d628c  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x46128c)
    #10 0x7f45522d529c  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x46029c)
    ....
    #251 0x7f45522d7e68  (/home/icy/secreal/libsass-asan/install/lib/libsass.so.1+0x462e68)

==102693==ABORTING


GDB debugging information:

(gdb) set args POC4
(gdb) b parser.cpp:66
(gdb) r
The program being debugged has been started already.
...
Breakpoint 1, Sass::Parser::advanceToNextToken (this=0x7fffffffd930) at parser.cpp:66
66       pstate.offset.line = 0;
(gdb) c 3025
Continuing.

Breakpoint 1, Sass::Parser::advanceToNextToken (this=0x7fffffffd930) at parser.cpp:66
66       pstate.offset.line = 0;
(gdb) n
r 
Program received signal SIGSEGV, Segmentation fault.
0x00000000004a6f1d in __asan_memset ()
(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   <MULTIPLE>         
 breakpoint already hit 3206 times
1.1                         y     0x00007ffff76c389a in Sass::Parser::advanceToNextToken() at parser.cpp:66
1.2                         y     0x00007ffff770d81f in Sass::Parser::parse_media_queries() at parser.cpp:66
1.3                         y     0x00007ffff77215d7 in Sass::Parser::parse_complex_selector(bool) 
                                                   at parser.cpp:66
1.4                         y     0x00007ffff7748276 in Sass::Parser::parse_disjunction() at parser.cpp:66
1.5                         y     0x00007ffff7749266 in Sass::Parser::parse_conjunction() at parser.cpp:66
1.6                         y     0x00007ffff774ae42 in Sass::Parser::parse_relation() at parser.cpp:66
1.7                         y     0x00007ffff774c5ea in Sass::Parser::parse_expression() at parser.cpp:66
1.8                         y     0x00007ffff7754a57 in Sass::Parser::parse_operators() at parser.cpp:66
1.9                         y     0x00007ffff777c695 in Sass::Parser::parse_media_query() at parser.cpp:66

(gdb) bt 
#0  0x00000000004a6f1d in __asan_memset ()
#1  0x00007ffff774827e in Sass::Parser::advanceToNextToken (this=0x7fffffffd930) at parser.cpp:66
#2  Sass::Parser::parse_disjunction (this=<optimized out>) at parser.cpp:1216
#3  0x00007ffff7711c1a in Sass::Parser::parse_space_list (this=0x7fffffffd930) at parser.cpp:1192
#4  0x00007ffff7746cdd in Sass::Parser::parse_comma_list (this=<optimized out>, delayed=false)
    at parser.cpp:1162
#5  0x00007ffff7741836 in Sass::Parser::parse_list (this=0x7fffffffd930, delayed=false) at parser.cpp:1147
#6  Sass::Parser::parse_map (this=<optimized out>) at parser.cpp:1058
#7  0x00007ffff775693b in Sass::Parser::parse_factor (this=0x7fffffffd930) at parser.cpp:1389
#8  0x00007ffff7754a82 in Sass::Parser::parse_operators (this=<optimized out>) at parser.cpp:1356
#9  0x00007ffff774c612 in Sass::Parser::parse_expression (this=<optimized out>) at parser.cpp:1316
#10 0x00007ffff774ae69 in Sass::Parser::parse_relation (this=<optimized out>) at parser.cpp:1262
#11 0x00007ffff774928d in Sass::Parser::parse_conjunction (this=<optimized out>) at parser.cpp:1240
#12 0x00007ffff774829d in Sass::Parser::parse_disjunction (this=<optimized out>) at parser.cpp:1219
#13 0x00007ffff7711c1a in Sass::Parser::parse_space_list (this=0x7fffffffd930) at parser.cpp:1192
#14 0x00007ffff7746cdd in Sass::Parser::parse_comma_list (this=<optimized out>, delayed=false)
    at parser.cpp:1162
...

This vulnerability was triggered in function Parser::advanceToNextToken() at line /libsass/src/parser.cpp:66:

  61    void Parser::advanceToNextToken() {
  62       lex < css_comments >(false);
  63       // advance to position
  64       pstate += pstate.offset;
  65       pstate.offset.column = 0;
  66       pstate.offset.line = 0;
  67     }


Actual results:

crash

Expected results:

crash

Additional info:

Credits:

This vulnerability is detected by team OWL337, with our custom fuzzer collAFL. Please contact ganshuitao   and chaoz.cn if you need more info about the team, the tool or the vulnerability.


Comments:
Comment 1
Aurelien Bompard 2017-07-18 13:24:25 UTC
Reported upstream as https://github.com/sass/libsass/issues/2447

---

Comment 2
Jan Kurik 2017-08-15 09:15:09 UTC
This bug appears to have been reported against 'rawhide' during the Fedora 27 development cycle.
Changing version to '27'.

---

Comment 3
Aurelien Bompard 2017-08-17 15:29:54 UTC
*** Bug 1482332 has been marked as a duplicate of this bug. ***

---

Comment 4
Ben Cotton 2018-11-27 18:28:11 UTC
This message is a reminder that Fedora 27 is nearing its end of life.
On 2018-Nov-30  Fedora will stop maintaining and issuing updates for
Fedora 27. It is Fedora's policy to close all bug reports from releases
that are no longer maintained. At that time this bug will be closed as
EOL if it remains open with a Fedora  'version' of '27'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 27 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

---

Comment 5
Ben Cotton 2022-07-11 19:33:47 UTC
It appears this bug was missed in the EOL closure for F27 on 2018-11-30. If this bug still exists on supported versions, please reopen and update the version. If you cannot update the version, please needinfo the assignee.

Attachments:
Attachment 1299843: Triggered by "./sassc POC4" [Link: https://bugzilla.redhat.com/attachment.cgi?id=1299843]

Build script:
#!/bin/bash -eu
# Minimized build script with only core build commands
set -eu
export BUILD='static'
make -j$(nproc)

Dockerfile:
FROM hwiwonlee/secb.base:latest
RUN apt-get update && apt-get install -y make autoconf automake libtool
RUN git clone https://github.com/sass/libsass libsass
RUN git -C libsass checkout 31573210c0d120ae56aaea543a0dbab5255cdfb7
WORKDIR $SRC/libsass
COPY build.sh $SRC/

Additional files:
filename: data_context_fuzzer.cc
content: #include "sass.h"

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
  char* sass_data = (char*) malloc(sizeof(char) * size + 1);
  if (sass_data == NULL) return 0;

  memcpy(sass_data, data, size);
  sass_data[size] = '\0';

  struct Sass_Data_Context* ctx = sass_make_data_context(sass_data);
  if (ctx == NULL) {
    free(sass_data);
    return 0;
  }

  struct Sass_Options* options = sass_make_options();
  if (options == NULL) {
    sass_delete_data_context(ctx);
    return 0;
  }

  sass_option_set_output_style(options, SASS_STYLE_NESTED);
  sass_option_set_precision(options, 5);

  sass_data_context_set_options(ctx, options);
  sass_compile_data_context(ctx);

  sass_delete_data_context(ctx);
  sass_delete_options(options);

  return 0;
}