AddressSanitizer: heap-use-after-free src/sass_context.cpp:75 in handle_error

[fgeek]

Tested commit: 43c4000
Credit: Henri Salo
Tools: american fuzzy lop 2.52b, afl-utils
Thanks to Kapsi internet-käyttäjät ry for providing valuable fuzzing resources.
sassc-2018-11-22.txt:

bod 0e
,,b,>,>,+,,E,%Ef0pkgrounH-{Oody:kg0V00:kg0000bodfbodf#{0000&}0pkgXounH-{olXr:(:00000&)}
@Xr:000000000}

=================================================================
==32534==ERROR: AddressSanitizer: heap-use-after-free on address 0x60700000b700 at pc 0x559ff2cf98c2 bp 0x7ffe8c8f3300 sp 0x7ffe8c8f32f8
READ of size 1 at 0x60700000b700 thread T0
    #0 0x559ff2cf98c1 in handle_error src/sass_context.cpp:75
    #1 0x559ff2cfc65c in handle_errors src/sass_context.cpp:207
    #2 0x559ff2d3f95b in sass_parse_block src/sass_context.cpp:253
    #3 0x559ff2d3f95b in sass_compiler_parse src/sass_context.cpp:483
    #4 0x559ff2d40a20 in sass_compile_context src/sass_context.cpp:371
    #5 0x559ff2d40a20 in sass_compile_file_context src/sass_context.cpp:470
    #6 0x559ff2d246b0 in compile_file /home/hsalo/src/sassc/sassc/sassc.c:158
    #7 0x559ff2cff82a in main /home/hsalo/src/sassc/sassc/sassc.c:370
    #8 0x7f191d31c2e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
    #9 0x559ff2d23d49 in _start (/home/hsalo/src/sassc/sassc/bin/sassc+0x84d49)

0x60700000b700 is located 0 bytes inside of 75-byte region [0x60700000b700,0x60700000b74b)
freed by thread T0 here:
    #0 0x7f191e1fda10 in free (/usr/lib/x86_64-linux-gnu/libasan.so.3+0xc1a10)
    #1 0x559ff31581c5 in Sass::Eval::operator()(Sass::Selector_Schema*) src/eval.cpp:1585
    #2 0x559ff348b282 in Sass::Selector_List::eval(Sass::Eval&) src/ast.cpp:1257
    #3 0x559ff31cf178 in Sass::Expand::operator()(Sass::Ruleset*) src/expand.cpp:108
    #4 0x559ff31f9340 in Sass::Expand::append_block(Sass::Block*) src/expand.cpp:802
    #5 0x559ff31f9340 in Sass::Expand::operator()(Sass::Block*) src/expand.cpp:72
    #6 0x559ff31d0b29 in Sass::Expand::operator()(Sass::Ruleset*) src/expand.cpp:144
    #7 0x559ff31f9340 in Sass::Expand::append_block(Sass::Block*) src/expand.cpp:802
    #8 0x559ff31f9340 in Sass::Expand::operator()(Sass::Block*) src/expand.cpp:72
    #9 0x559ff2d79af8 in Sass::Context::compile() src/context.cpp:678
    #10 0x559ff2d7ea1c in Sass::File_Context::parse() src/context.cpp:605
    #11 0x559ff2d3ee11 in sass_parse_block src/sass_context.cpp:234
    #12 0x559ff2d3ee11 in sass_compiler_parse src/sass_context.cpp:483
    #13 0x559ff2d40a20 in sass_compile_context src/sass_context.cpp:371
    #14 0x559ff2d40a20 in sass_compile_file_context src/sass_context.cpp:470
    #15 0x559ff2d246b0 in compile_file /home/hsalo/src/sassc/sassc/sassc.c:158

previously allocated by thread T0 here:
    #0 0x7f191e1fdd28 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.3+0xc1d28)
    #1 0x559ff2d26760 in sass_alloc_memory src/sass.cpp:36
    #2 0x559ff2d267e2 in sass_copy_c_string src/sass.cpp:47
    #3 0x559ff315723c in Sass::Eval::operator()(Sass::Selector_Schema*) src/eval.cpp:1565
    #4 0x559ff348b282 in Sass::Selector_List::eval(Sass::Eval&) src/ast.cpp:1257
    #5 0x559ff31cf178 in Sass::Expand::operator()(Sass::Ruleset*) src/expand.cpp:108
    #6 0x559ff31f9340 in Sass::Expand::append_block(Sass::Block*) src/expand.cpp:802
    #7 0x559ff31f9340 in Sass::Expand::operator()(Sass::Block*) src/expand.cpp:72
    #8 0x559ff31d0b29 in Sass::Expand::operator()(Sass::Ruleset*) src/expand.cpp:144
    #9 0x559ff31f9340 in Sass::Expand::append_block(Sass::Block*) src/expand.cpp:802
    #10 0x559ff31f9340 in Sass::Expand::operator()(Sass::Block*) src/expand.cpp:72
    #11 0x559ff2d79af8 in Sass::Context::compile() src/context.cpp:678
    #12 0x559ff2d7ea1c in Sass::File_Context::parse() src/context.cpp:605
    #13 0x559ff2d3ee11 in sass_parse_block src/sass_context.cpp:234
    #14 0x559ff2d3ee11 in sass_compiler_parse src/sass_context.cpp:483
    #15 0x559ff2d40a20 in sass_compile_context src/sass_context.cpp:371
    #16 0x559ff2d40a20 in sass_compile_file_context src/sass_context.cpp:470
    #17 0x559ff2d246b0 in compile_file /home/hsalo/src/sassc/sassc/sassc.c:158

SUMMARY: AddressSanitizer: heap-use-after-free src/sass_context.cpp:75 in handle_error
Shadow bytes around the buggy address:
  0x0c0e7fff9690: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff96a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff96b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff96c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0e7fff96d0: fa fa fd fd fd fd fd fd fd fd fd fd fa fa fa fa
=>0x0c0e7fff96e0:[fd]fd fd fd fd fd fd fd fd fd fa fa fa fa fd fd
  0x0c0e7fff96f0: fd fd fd fd fd fd fd fd fa fa fa fa fd fd fd fd
  0x0c0e7fff9700: fd fd fd fd fd fd fa fa fa fa fd fd fd fd fd fd
  0x0c0e7fff9710: fd fd fd fd fa fa fa fa fd fd fd fd fd fd fd fd
  0x0c0e7fff9720: fd fd fa fa fa fa fd fd fd fd fd fd fd fd fd fd
  0x0c0e7fff9730: fa fa fa fa fd fd fd fd fd fd fd fd fd 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
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  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
==32534==ABORTING