https://bugs.exim.org/show_bug.cgi?id=2484
Bug ID: 2484
Summary: Stack overflow in internal_dfa_match()
(pcre2_dfa_match.c)
Product: PCRE
Version: 10.34 (PCRE2)
Hardware: x86
OS: All
Status: NEW
Severity: bug
Priority: medium
Component: Code
Assignee: p...@hermes.cam.ac.uk
Reporter: clickwit...@gmail.com
CC: pcre-dev@exim.org
Created attachment 1238
--> https://bugs.exim.org/attachment.cgi?id=1238&action=edit
Crash input file that triggers the bug
The latest version of PCRE (pcre2-10.34-RC1, pcre2-10.33) is prone to a stack
overflow vulnerability in internal_dfa_match() (pcre2_dfa_match.c) which can be
triggered using a crafted regular expression. Upon execution of the crafted
regular expression, the function internal_dfa_match() calls itself recursively,
resulting into uncontrolled recursion. It exceeds the stack size limit (8 MB),
finally resulting into stack exhaustion. An attacker can potentially exploit
this issue to perform remote code execution or denial of service attack.
=====================
Output of ASAN compiled library (-fsanitize=address)
Run as: ./pcre2test sbovf-input (attached herewith)
--------------------
ASAN:DEADLYSIGNAL
==17245==ERROR: AddressSanitizer: stack-overflow on address 0x7fffff7feff8 (pc
0x5555555afcc7 bp 0x7fffff7ff4b0 sp 0x7fffff7fefe0 T0)
#0 0x5555555afcc6 in internal_dfa_match src/pcre2_dfa_match.c:2859
#1 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#2 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#3 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#4 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#5 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#6 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#7 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#8 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#9 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#10 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
...
<skipped>
...
#240 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#241 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#242 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#243 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#244 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#245 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#246 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#247 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#248 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#249 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
#250 0x5555555b4020 in internal_dfa_match src/pcre2_dfa_match.c:2871
SUMMARY: AddressSanitizer: stack-overflow src/pcre2_dfa_match.c:2859 in
internal_dfa_match
==17245==ABORTING
====================
With gdb
--------------------
$ gdb ./pcre2test
(gdb) r sbovf-input
Program received signal SIGSEGV, Segmentation fault.
0x00005555555aaab4 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eb1 '\200' <repeats 200
times>..., start_offset=start_offset@entry=6522,
offsets=offsets@entry=0x7fffec780030, offsetcount=offsetcount@entry=1000,
workspace=0x7fffec781f70, wscount=1000, rlevel=6522, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:533
(gdb) bt 10
#0 0x00005555555aaab4 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eb1 '\200' <repeats 200
times>..., start_offset=start_offset@entry=6522,
offsets=offsets@entry=0x7fffec780030, offsetcount=offsetcount@entry=1000,
workspace=0x7fffec781f70, wscount=1000, rlevel=6522, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:533
#1 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eb0 '\200' <repeats 200
times>..., start_offset=start_offset@entry=6521,
offsets=offsets@entry=0x7fffec77d150, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6522, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#2 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eaf '\200' <repeats 200
times>..., start_offset=start_offset@entry=6520,
offsets=offsets@entry=0x7fffec77a270, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6521, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#3 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eae '\200' <repeats 200
times>..., start_offset=start_offset@entry=6519,
offsets=offsets@entry=0x7fffec777390, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6520, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#4 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002ead '\200' <repeats 200
times>..., start_offset=start_offset@entry=6518,
offsets=offsets@entry=0x7fffec7744b0, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6519, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#5 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eac '\200' <repeats 200
times>..., start_offset=start_offset@entry=6517,
offsets=offsets@entry=0x7fffec7715d0, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6518, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#6 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eab '\200' <repeats 200
times>..., start_offset=start_offset@entry=6516,
offsets=offsets@entry=0x7fffec76e6f0, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6517, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#7 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002eaa '\200' <repeats 200
times>..., start_offset=start_offset@entry=6515,
offsets=offsets@entry=0x7fffec76b810, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6516, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#8 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002ea9 '\200' <repeats 200
times>..., start_offset=start_offset@entry=6514,
offsets=offsets@entry=0x7fffec768930, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6515, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
#9 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000002ea8 '\200' <repeats 200
times>..., start_offset=start_offset@entry=6513,
offsets=offsets@entry=0x7fffec765a50, offsetcount=offsetcount@entry=1000,
workspace=<optimized out>, wscount=166, rlevel=6514, RWS=0x7fffeb8c5800) at
src/pcre2_dfa_match.c:2871
(More stack frames follow...)
(gdb) bt -10
#6516 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x62900000153d ")* # If comment
found, al", '\200' <repeats 172 times>..., start_offset=start_offset@entry=6,
offsets=offsets@entry=0x6300001a90b0,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=7, RWS=0x6300001a0400) at src/pcre2_dfa_match.c:2871
#6517 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x62900000153c " )* # If comment
found, al", '\200' <repeats 171 times>..., start_offset=start_offset@entry=5,
offsets=offsets@entry=0x6300001a61d0,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=6, RWS=0x6300001a0400) at src/pcre2_dfa_match.c:2871
#6518 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x62900000153b "* )* # If comment
found, al", '\200' <repeats 170 times>..., start_offset=start_offset@entry=4,
offsets=offsets@entry=0x6300001a32f0,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=5, RWS=0x6300001a0400) at src/pcre2_dfa_match.c:2871
#6519 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x62900000153a "]* )* # If comment
found, al", '\200' <repeats 169 times>..., start_offset=start_offset@entry=3,
offsets=offsets@entry=0x6300001a0410,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=4, RWS=0x6300001a0400) at src/pcre2_dfa_match.c:2871
#6520 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000001539 "\t]* )* # If
comment found, al", '\200' <repeats 168 times>...,
start_offset=start_offset@entry=2, offsets=offsets@entry=0x7fffffff87d0,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=3, RWS=0x6300001a0400) at src/pcre2_dfa_match.c:2871
#6521 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=this_start_code@entry=0x611000000acf "\210",
current_subject=current_subject@entry=0x629000001538 " \t]* )* # If
comment found, al", '\200' <repeats 167 times>...,
start_offset=start_offset@entry=1, offsets=offsets@entry=0x7fffffff58f0,
offsetcount=offsetcount@entry=1000, workspace=<optimized out>, wscount=166,
rlevel=2, RWS=0x7fffffff58e0) at src/pcre2_dfa_match.c:2871
#6522 0x00005555555b4021 in internal_dfa_match (mb=mb@entry=0x7fffffff5800,
this_start_code=<optimized out>,
current_subject=current_subject@entry=0x629000001537 "[ \t]* )* # If
comment found, al", '\200' <repeats 166 times>...,
start_offset=start_offset@entry=0, offsets=offsets@entry=0x612000000090,
offsetcount=30, workspace=<optimized out>, wscount=166, rlevel=1,
RWS=0x7fffffff58e0) at src/pcre2_dfa_match.c:2871
#6523 0x00005555555bdb07 in pcre2_dfa_match_8 (code=<optimized out>,
subject=<optimized out>, length=11465, start_offset=<optimized out>, options=0,
match_data=<optimized out>, mcontext=<optimized out>,
workspace=<optimized out>, wscount=<optimized out>) at
src/pcre2_dfa_match.c:3885
#6524 0x0000555555576bc2 in process_data () at src/pcre2test.c:7522
#6525 0x000055555557cd62 in main (argc=<optimized out>, argv=<optimized out>)
at src/pcre2test.c:9002
====================
Crash triage:
--------------------
Function: internal_dfa_match() recursively calls itself at
src/pcre2_dfa_match.c:2871, exceeding the stack size limit (8 MB), thus
resulting into stack corruption (exhaustion).
(gdb) list src/pcre2_dfa_match.c:2871
2866 new_recursive.group_num = recno;
2867 new_recursive.subject_position = ptr;
2868 new_recursive.prevrec = mb->recursive;
2869 mb->recursive = &new_recursive;
2870
2871 rc = internal_dfa_match(
2872 mb, /* fixed match data */
2873 callpat, /* this subexpression's
code */
2874 ptr, /* where we currently
are */
2875 (PCRE2_SIZE)(ptr - start_subject), /* start offset */
2876 local_offsets, /* offset vector */
2877 RWS_OVEC_RSIZE/OVEC_UNIT, /* size of same */
2878 local_workspace, /* workspace vector */
2879 RWS_RSIZE, /* size of same */
2880 rlevel, /* function recursion
level */
2881 RWS); /* recursion workspace
*/
====================
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