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tpm2: Fix some ASN.1 related code

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Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
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Stefan Berger 2019-10-23 16:06:39 -04:00 committed by Stefan Berger
parent b822e395c3
commit 1cbee17a16
1 changed files with 28 additions and 22 deletions
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50
src/tpm2/TpmAsn1.c
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@ -3,7 +3,7 @@
/* TPM ASN.1 */
/* Written by Ken Goldman */
/* IBM Thomas J. Watson Research Center */
/* $Id: TpmAsn1.c 1490 2019-07-26 21:13:22Z kgoldman $ */
/* $Id: TpmAsn1.c 1509 2019-10-07 19:10:05Z kgoldman $ */
/* */
/* Licenses and Notices */
/* */
@ -178,33 +178,39 @@ ASN1GetBitStringValue(
int shift;
INT16 length;
UINT32 value = 0;
//
VERIFY((length = ASN1NextTag(ctx)) >= 1);
int inputBits;
//
length = ASN1NextTag(ctx);
VERIFY(length >= 1);
VERIFY(ctx->tag == ASN1_BITSTRING);
// Get the shift value for the bit field (how many bits to loop off of the end)
// Get the shift value for the bit field (how many bits to lop off of the end)
shift = NEXT_OCTET(ctx);
length--;
// Get the number of bits in the input
inputBits = (8 * length) - shift;
// the shift count has to make sense
VERIFY((shift < 8) && ((length > 0) || (shift == 0)));
// if there are any bytes left
for(; length > 0; length--)
{
if(length > 1)
{
// for all but the last octet, just shift and add the new octet
VERIFY((value & 0xFF000000) == 0); // can't loose significant bits
value = (value << 8) + NEXT_OCTET(ctx);
}
else
{
// for the last octet, just shift the accumulated value enough to
// accept the significant bits in the last octet and shift the last
// octet down
VERIFY(((value & (0xFF000000 << (8 - shift)))) == 0);
value = (value << (8 - shift)) + (NEXT_OCTET(ctx) >> shift);
}
}
for(; length > 1; length--)
{
// for all but the last octet, just shift and add the new octet
VERIFY((value & 0xFF000000) == 0); // can't loose significant bits
value = (value << 8) + NEXT_OCTET(ctx);
}
if(length == 1)
{
// for the last octet, just shift the accumulated value enough to
// accept the significant bits in the last octet and shift the last
// octet down
VERIFY(((value & (0xFF000000 << (8 - shift)))) == 0);
value = (value << (8 - shift)) + (NEXT_OCTET(ctx) >> shift);
}
// 'Left justify' the result
if(inputBits > 0)
value <<= (32 - inputBits);
*val = value;
return TRUE;
Error: