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udhcp: fix a SEGV on malformed RFC1035-encoded domain name

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-03-10 11:47:58 +01:00
parent d2b820b540
commit d474ffc682
1 changed files with 9 additions and 4 deletions
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13
networking/udhcp/domain_codec.c
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@ -63,11 +63,10 @@ char* FAST_FUNC dname_dec(const uint8_t *cstr, int clen, const char *pre)
if (crtpos + *c + 1 > clen) /* label too long? abort */
return NULL;
if (dst)
memcpy(dst + len, c + 1, *c);
/* \3com ---> "com." */
((char*)mempcpy(dst + len, c + 1, *c))[0] = '.';
len += *c + 1;
crtpos += *c + 1;
if (dst)
dst[len - 1] = '.';
} else {
/* NUL: end of current domain name */
if (retpos == 0) {
@ -78,7 +77,10 @@ char* FAST_FUNC dname_dec(const uint8_t *cstr, int clen, const char *pre)
crtpos = retpos;
retpos = depth = 0;
}
if (dst)
if (dst && len != 0)
/* \4host\3com\0\4host and we are at \0:
* \3com was converted to "com.", change dot to space.
*/
dst[len - 1] = ' ';
}
@ -227,6 +229,9 @@ int main(int argc, char **argv)
int len;
uint8_t *encoded;
uint8_t str[6] = { 0x00, 0x00, 0x02, 0x65, 0x65, 0x00 };
printf("NUL:'%s'\n", dname_dec(str, 6, ""));
#define DNAME_DEC(encoded,pre) dname_dec((uint8_t*)(encoded), sizeof(encoded), (pre))
printf("'%s'\n", DNAME_DEC("\4host\3com\0", "test1:"));
printf("test2:'%s'\n", DNAME_DEC("\4host\3com\0\4host\3com\0", ""));