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asn1: tagnum size has not exceed 3 bytes 

3 bytes is the size of SC_ASN1_TAG_MASK used when composing
the asn1 templates with 'struct sc_asn1_entry'.
With this limitation maximal supported ASN.1 tag number is 2^^14-1 .

Fixed 'dead-code' coverity-scan issue.

Close #707
This commit is contained in:
Viktor Tarasov 2016-03-09 18:38:31 +01:00
parent 196e476330
commit f98c8cd37c
2 changed files with 7 additions and 5 deletions
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11
src/libopensc/asn1.c
View File

@ -73,14 +73,17 @@ int sc_asn1_read_tag(const u8 ** buf, size_t buflen, unsigned int *cla_out,
*tag_out = SC_ASN1_TAG_EOC;
return SC_SUCCESS;
}
/* parse tag byte(s) */
/* parse tag byte(s)
* Resulted tag is presented by integer that has not to be
* confused with the 'tag number' part of ASN.1 tag.
*/
cla = (*p & SC_ASN1_TAG_CLASS) | (*p & SC_ASN1_TAG_CONSTRUCTED);
tag = *p & SC_ASN1_TAG_PRIMITIVE;
p++;
left--;
if (tag == SC_ASN1_TAG_PRIMITIVE) {
/* high tag number */
size_t n = sizeof(int) - 1;
size_t n = SC_ASN1_TAGNUM_SIZE - 1;
/* search the last tag octet */
while (left-- != 0 && n != 0) {
tag <<= 8;
@ -93,10 +96,8 @@ int sc_asn1_read_tag(const u8 ** buf, size_t buflen, unsigned int *cla_out,
/* either an invalid tag or it doesn't fit in
* unsigned int */
return SC_ERROR_INVALID_ASN1_OBJECT;
}
if (left == 0)
return SC_ERROR_INVALID_ASN1_OBJECT;
/* parse length byte(s) */
len = *p & 0x7f;
if (*p++ & 0x80) {

1
src/libopensc/asn1.h
View File

@ -135,6 +135,7 @@ int sc_asn1_sig_value_sequence_to_rs(struct sc_context *ctx,
#define SC_ASN1_CONS 0x01000000
#define SC_ASN1_TAG_MASK 0x00FFFFFF
#define SC_ASN1_TAGNUM_SIZE 3
#define SC_ASN1_PRESENT 0x00000001
#define SC_ASN1_OPTIONAL 0x00000002