[Bug libstdc++/103955] std::to_chars(char*, char*, double, std::chars_format, int precision) crashes for the two maximal int precision values

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103955

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-01-09
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
With  -fsanitize=address I get:



=================================================================
==1==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd6d9523d7
at pc 0x7f37917b829e bp 0x7ffd6d9522c0 sp 0x7ffd6d951a70
WRITE of size 2147483594 at 0x7ffd6d9523d7 thread T0
    #0 0x7f37917b829d in __interceptor_memset
(/opt/compiler-explorer/gcc-11.2.0/lib64/libasan.so.6+0x3c29d)
    #1 0x7f37916cafa6 
(/opt/compiler-explorer/gcc-11.2.0/lib64/libstdc++.so.6+0x162fa6)
    #2 0x7f37916cb48c in std::to_chars(char*, char*, double, std::chars_format,
int) (/opt/compiler-explorer/gcc-11.2.0/lib64/libstdc++.so.6+0x16348c)
    #3 0x4010fa in main /app/example.cpp:9
    #4 0x7f37908c20b2 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
    #5 0x4011ed in _start (/app/output.s+0x4011ed)

Address 0x7ffd6d9523d7 is located in stack of thread T0 at offset 103 in frame
    #0 0x40107f in main /app/example.cpp:5

  This frame has 1 object(s):
    [48, 84) 'result' (line 6) <== Memory access at offset 103 overflows this
variable
HINT: this may be a false positive if your program uses some custom stack
unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow
(/opt/compiler-explorer/gcc-11.2.0/lib64/libasan.so.6+0x3c29d) in
__interceptor_memset
Shadow bytes around the buggy address:
  0x10002db22420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db22430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db22440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db22450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db22460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
=>0x10002db22470: f1 f1 f1 f1 00 00 00 00 04 f3[f3]f3 f3 f3 00 00
  0x10002db22480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db22490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db224a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db224b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10002db224c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
  Shadow gap:              cc
==1==ABORTING