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Fix fuzzing errors

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We should be checking for integer overflow, rather than checking if size is 0.

Additionally, we should set errno to ENOMEM when this overflow happens.

Finally, the most efficient implementation of the round-up-to-2 algorithm involves the clz intrinsic.
This commit is contained in:
Rose
2023-07-03 22:03:39 -04:00
parent 9266966ab9
commit 732110428e
3 changed files with 21 additions and 11 deletions
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18
lib/util/parseln.c
View File

@@ -23,10 +23,11 @@
#include <config.h>
#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#ifdef HAVE_STDBOOL_H
# include <stdbool.h>
#else
@@ -91,9 +92,20 @@ sudo_parseln_v2(char **bufp, size_t *bufsizep, unsigned int *lineno, FILE *fp, i
if (*bufp == NULL || total + len >= *bufsizep) {
void *newbuf;
const size_t newsize = sudo_pow2_roundup(total + len + 1);
const size_t size = total + len + 1;
const size_t newsize = sudo_pow2_roundup(size);
if (newsize == 0 || (newbuf = realloc(*bufp, newsize)) == NULL) {
if (newsize < size) {
/* overflow */
errno = ENOMEM;
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"unable to allocate memory");
len = -1;
total = 0;
break;
}
if ((newbuf = realloc(*bufp, newsize)) == NULL) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"unable to allocate memory");
len = -1;

12
lib/util/roundup.c
View File

@@ -47,14 +47,10 @@ sudo_pow2_roundup_v2(size_t len)
{
if (len < 64)
return 64;
len--;
len |= len >> 1;
len |= len >> 2;
len |= len >> 4;
len |= len >> 8;
len |= len >> 16;
#ifdef __LP64__
len |= len >> 32;
return 1 << (64 - __builtin_clzl(len - 1));
#else
return 1 << (32 - __builtin_clz(len - 1));
#endif
return ++len;
}

2
logsrvd/logsrvd_journal.c
View File

@@ -270,11 +270,13 @@ journal_seek(struct timespec *target, struct connection_closure *closure)
bufsize = sudo_pow2_roundup(msg_len);
if (bufsize < msg_len) {
/* overflow */
errno = ENOMEM;
closure->errstr = _("unable to allocate memory");
break;
}
free(buf);
if ((buf = malloc(bufsize)) == NULL) {
errno = ENOMEM;
closure->errstr = _("unable to allocate memory");
break;
}