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Vet lengths of property lists in crypto deserialization

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The memory allocation in deserializing property lists within the crypto
code should not trust the deserialized length and try to allocate that
much memory but should first verify that the length is consistent with
the number of bytes remaining in the input.  (Noted by Coverity as use
of tainted data.)

Signed-off-by: Erik Boasson <eb@ilities.com>
This commit is contained in:
Erik Boasson 2020-05-06 21:45:56 +02:00 • committed by eboasson
parent 59a2b9d273
commit fa7999c5d8
1 changed files with 17 additions and 6 deletions
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23
src/security/core/src/dds_security_serialize.c
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@ -627,14 +627,20 @@ DDS_Security_Deserialize_PropertySeq(
DDS_Security_Deserializer dser, DDS_Security_Deserializer dser,
DDS_Security_PropertySeq *seq) DDS_Security_PropertySeq *seq)
{ {
/* A well-formed CDR string is length + content including terminating 0, length is
4 bytes and 4-byte aligned, so the minimum length for a non-empty property
sequence is 4+1+(3 pad)+4+1 = 13 bytes. Just use 8 because it is way faster
and just as good for checking that the length value isn't completely ridiculous. */
const uint32_t minpropsize = (uint32_t) (2 * sizeof (uint32_t));
int r = 1; int r = 1;
uint32_t i; uint32_t i;
if (!DDS_Security_Deserialize_uint32_t(dser, &seq->_length)) { if (!DDS_Security_Deserialize_uint32_t(dser, &seq->_length)) {
return 0; return 0;
} } else if (seq->_length > dser->remain / minpropsize) {
seq->_length = 0;
if (seq->_length > 0) { return 0;
} else if (seq->_length > 0) {
seq->_buffer = DDS_Security_PropertySeq_allocbuf(seq->_length); seq->_buffer = DDS_Security_PropertySeq_allocbuf(seq->_length);
for (i = 0; i < seq->_length && r; i++) { for (i = 0; i < seq->_length && r; i++) {
r = DDS_Security_Deserialize_Property(dser, &seq->_buffer[i]); r = DDS_Security_Deserialize_Property(dser, &seq->_buffer[i]);
@ -649,14 +655,19 @@ DDS_Security_Deserialize_BinaryPropertySeq(
DDS_Security_Deserializer dser, DDS_Security_Deserializer dser,
DDS_Security_BinaryPropertySeq *seq) DDS_Security_BinaryPropertySeq *seq)
{ {
/* A well-formed CDR string + a well-formed octet sequence: 4+1+(3 pad)+4 = 12 bytes.
Just use 8 because it is way faster and just as good for checking that the length
value isn't completely ridiculous. */
const uint32_t minpropsize = (uint32_t) (2 * sizeof (uint32_t));
int r = 1; int r = 1;
uint32_t i; uint32_t i;
if (!DDS_Security_Deserialize_uint32_t(dser, &seq->_length)) { if (!DDS_Security_Deserialize_uint32_t(dser, &seq->_length)) {
return 0; return 0;
} } else if (seq->_length > dser->remain / minpropsize) {
seq->_length = 0;
if (seq->_length > 0) { return 0;
} else if (seq->_length > 0) {
seq->_buffer = DDS_Security_BinaryPropertySeq_allocbuf(seq->_length); seq->_buffer = DDS_Security_BinaryPropertySeq_allocbuf(seq->_length);
for (i = 0; i < seq->_length && r; i++) { for (i = 0; i < seq->_length && r; i++) {
r = DDS_Security_Deserialize_BinaryProperty(dser, &seq->_buffer[i]); r = DDS_Security_Deserialize_BinaryProperty(dser, &seq->_buffer[i]);