Public bug reported:
Hi,
I am learning C and had a strange bug when allocating values into some calloc'd
memory with fscanf.
Later calls to fscanf would overwrite previously set values to zero. I am
using an AMD athlon 64 bit cpu on
a 32bit Fiesty Fawn version of Ubuntu and I think that the std library must be
ignoring the type conversion modifier
and just writing a larger type into the memory.
Attached is a simple program called fscanfbug.c which reproduces the problem.
Is this something I should just work around or should this be fixed in glibc?
Thanks,
Alysander
//Number 5
#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
int main (int argc, char *argv[]) {
int8_t *numarray = NULL;
FILE *numfile = NULL;
numarray = calloc(10, sizeof(int8_t));
numfile = fopen("fscanfbug.c", "r");
fscanf(numfile, "//Number %"PRId8, &numarray[8]);
fscanf(numfile, "//Number %"PRId8, &numarray[7]);
printf("The 8th number is: %"PRId8"\n", numarray[8]);
printf("The 7th number is: %"PRId8" (shouldn't this be the same as above?)
\n", numarray[7]);
fclose(numfile);
free(numarray);
return 1;
}
** Affects: glibc (Ubuntu)
Importance: Undecided
Status: Unconfirmed
--
fscanf out of bounds write
https://bugs.launchpad.net/bugs/110917
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