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Reduce size of mbedtls_asn1_get_len

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Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-09-12 14:42:46 +01:00
parent d3450da98d
commit ef6795d2a9
1 changed files with 12 additions and 41 deletions
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53
library/asn1parse.c
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@ -47,47 +47,18 @@ int mbedtls_asn1_get_len(unsigned char **p,
if ((**p & 0x80) == 0) {
*len = *(*p)++;
} else {
switch (**p & 0x7F) {
case 1:
if ((end - *p) < 2) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = (*p)[1];
(*p) += 2;
break;
case 2:
if ((end - *p) < 3) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 8) | (*p)[2];
(*p) += 3;
break;
case 3:
if ((end - *p) < 4) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 16) |
((size_t) (*p)[2] << 8) | (*p)[3];
(*p) += 4;
break;
case 4:
if ((end - *p) < 5) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = ((size_t) (*p)[1] << 24) | ((size_t) (*p)[2] << 16) |
((size_t) (*p)[3] << 8) | (*p)[4];
(*p) += 5;
break;
default:
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
int n = (**p) & 0x7F;
if (n == 0 || n > 4) {
return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
}
if ((end - *p) <= n) {
return MBEDTLS_ERR_ASN1_OUT_OF_DATA;
}
*len = 0;
(*p)++;
while (n--) {
*len = (*len << 8) | **p;
(*p)++;
}
}