Re: Help understanding some valgrind output
Derrick McKee <[email protected]>
| Newsgroups | gmane.comp.debugging.valgrind |
|---|---|
| Message-ID | <CAJoBWHxjo-0=hSPewrkm=AVvxJ0Th+5SwD-bvW7qacMeOSPQEg@mail.gmail.com> |
Oh sorry, you're trying to write 8201 bytes into an 8200 byte buffer. On Thu, Jun 4, 2020, 22:36 Derrick McKee <[email protected]> wrote: > It looks like html_link_find is allocating a buffer of size 0, and then > you are trying to write 1 byte to it. > > On Thu, Jun 4, 2020, 22:28 James Read <[email protected]> wrote: > >> Here is my valgrind output that I don't understand: >> >> ==319842== Invalid write of size 1 >> ==319842== at 0x48436E4: mempcpy (in >> /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so) >> ==319842== by 0x50CD1D8: _IO_default_xsputn (genops.c:386) >> ==319842== by 0x50CD1D8: _IO_default_xsputn (genops.c:370) >> ==319842== by 0x50B227B: __vfprintf_internal (vfprintf-internal.c:1688) >> ==319842== by 0x50C0278: __vsprintf_internal (iovsprintf.c:95) >> ==319842== by 0x509D047: sprintf (sprintf.c:30) >> ==319842== by 0x10B88F: html_link_find (crawler.c:452) >> ==319842== by 0x10BD6F: html_parse (crawler.c:536) >> ==319842== by 0x10C2CB: check_multi_info (crawler.c:678) >> ==319842== by 0x10C3DA: event_cb (crawler.c:706) >> ==319842== by 0x10D828: crawler_init (crawler.c:1154) >> ==319842== by 0x10DAE8: main (crawler.c:1207) >> ==319842== Address 0xf107d18 is 0 bytes after a block of size 8,200 >> alloc'd >> ==319842== at 0x483B7F3: malloc (in >> /usr/lib/x86_64-linux-gnu/valgrind/vgpreload_memcheck-amd64-linux.so) >> ==319842== by 0x10B736: html_link_find (crawler.c:440) >> ==319842== by 0x10BD6F: html_parse (crawler.c:536) >> ==319842== by 0x10C2CB: check_multi_info (crawler.c:678) >> ==319842== by 0x10C3DA: event_cb (crawler.c:706) >> ==319842== by 0x10D828: crawler_init (crawler.c:1154) >> ==319842== by 0x10DAE8: main (crawler.c:1207) >> ==319842== >> >> valgrind: m_mallocfree.c:305 (get_bszB_as_is): Assertion 'bszB_lo == >> bszB_hi' failed. >> valgrind: Heap block lo/hi size mismatch: lo = 8272, hi = >> 3625731377157460067. >> This is probably caused by your program erroneously writing past the >> end of a heap block and corrupting heap metadata. If you fix any >> invalid writes reported by Memcheck, this assertion failure will >> probably go away. Please try that before reporting this as a bug. >> >> The code this pertains to can be found at >> https://github.com/JamesRead5737/webcrawler >> >> Any help in understanding what this error means would be greatly >> appreciated. >> >> James Read >> _______________________________________________ >> Valgrind-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/valgrind-users >> > _______________________________________________ Valgrind-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/valgrind-users