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Check for overflow when using k, M or G

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Check that using a postfix (k, M, G) with repeat count does not cause
overflow in the int mtop.mt_count.
This commit is contained in:
Kai Mäkisara
2016-02-11 13:45:33 +02:00
committed by Iustin Pop
parent b48a42742f
commit dd5afc0eb6
1 changed files with 16 additions and 3 deletions
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19
mt.c
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@@ -16,6 +16,7 @@
#include <ctype.h> #include <ctype.h>
#include <errno.h> #include <errno.h>
#include <fcntl.h> #include <fcntl.h>
#include <limits.h>
#include <sys/types.h> #include <sys/types.h>
#include <sys/ioctl.h> #include <sys/ioctl.h>
#include <sys/stat.h> #include <sys/stat.h>
@@ -444,18 +445,30 @@ usage(int explain)
static int static int
do_standard(int mtfd, cmdef_tr *cmd, int argc, char **argv) do_standard(int mtfd, cmdef_tr *cmd, int argc, char **argv)
{ {
int multiplier, max_count;
struct mtop mt_com; struct mtop mt_com;
char *endp; char *endp;
mt_com.mt_op = cmd->cmd_code; mt_com.mt_op = cmd->cmd_code;
mt_com.mt_count = (argc > 0 ? strtol(*argv, &endp, 0) : 1); mt_com.mt_count = (argc > 0 ? strtol(*argv, &endp, 0) : 1);
if (argc > 0 && endp != *argv) { if (argc > 0 && endp != *argv) {
multiplier = 1;
if (*endp == 'k') if (*endp == 'k')
mt_com.mt_count *= 1024; multiplier = 1024;
else if (*endp == 'M') else if (*endp == 'M')
mt_com.mt_count *= 1024 * 1024; multiplier = 1024 * 1024;
else if (*endp == 'G') else if (*endp == 'G')
mt_com.mt_count *= 1024 * 1024 * 1024; multiplier = 1024 * 1024 * 1024;
else if (*endp != 0) {
fprintf(stderr, "mt: illegal count unit.\n");
return 3;
}
max_count = INT_MAX / multiplier;
if (mt_com.mt_count > max_count) {
fprintf(stderr, "mt: repeat count too large.\n");
return 3;
}
mt_com.mt_count *= multiplier;
} }
mt_com.mt_count |= cmd->cmd_count_bits; mt_com.mt_count |= cmd->cmd_count_bits;
if (mt_com.mt_count < 0) { if (mt_com.mt_count < 0) {