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fixed undefined behavior when parsing negative ASN.1 Integer

This commit is contained in:
Frank Morgner 2019-08-29 11:15:29 +02:00
parent 3e110995bc
commit f621305140
1 changed files with 4 additions and 2 deletions
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6
src/libopensc/asn1.c
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@ -707,17 +707,19 @@ static int encode_bit_field(const u8 *inbuf, size_t inlen,
int sc_asn1_decode_integer(const u8 * inbuf, size_t inlen, int *out) int sc_asn1_decode_integer(const u8 * inbuf, size_t inlen, int *out)
{ {
int a = 0; int a = 0, is_negative = 0;
size_t i; size_t i;
if (inlen > sizeof(int) || inlen == 0) if (inlen > sizeof(int) || inlen == 0)
return SC_ERROR_INVALID_ASN1_OBJECT; return SC_ERROR_INVALID_ASN1_OBJECT;
if (inbuf[0] & 0x80) if (inbuf[0] & 0x80)
a = -1; is_negative = 1;
for (i = 0; i < inlen; i++) { for (i = 0; i < inlen; i++) {
a <<= 8; a <<= 8;
a |= *inbuf++; a |= *inbuf++;
} }
if (is_negative)
a *= -1;
*out = a; *out = a;
return 0; return 0;
} }