[Date Prev][Date Next]
(ITS#5010) broken ber_encode_oid/ber_decode_oid()
Full_Name: Hallvard B Furuseth
Submission from: (NULL) (220.127.116.11)
Submitted by: hallvard
The 40*X+Y rule for first 2 components is decoded wrong, it should be
X = val < 80 ? val/40 : 2 # X = 0, 1 or 2
Y = val - 40*X # Y is unlimited when X==2, <40 otherwise
See X.690 8.19.4: ... (X*40) + Y: NOTE - This packing of the first two
object identifier components recognizes that only three values are
allocated from the root node, and at most 39 subsequent values from
nodes reached by X = 0 and X = 1.
40*X+Y can take more than one octet.
The functions allow buffer overruns. ber_decode_oid() if the oid has
many small components. ber_encode_oid() for negative input (which
becomes a large ulong), or if sizeof(long) == 8. The latter can just as
easily be avoided by producing the bytes backwards and then reversing.
They do not check much for invalid input or too large values. Possibly
they ought to be a bit paranoid about that since they are used for
certificates, I don't know. E.g. check that the BER encoding has
"fewest possible octets" (X.690 8.19.2), i.e. no initial 0x80 in
subidentifiers. ber_encode_oid() seems a bit strange about which errors
it accepts and which ones it rejects. E.g. garbage after first 2
components is OK.
The "assert(foo != NULL)"s are after "der = foo->bv_val":-)
I enclose untested new versions. Will test and commit when I have time
if someone says OK, but it depends e.g. on how paranoid the routines
should or should not be. Or if they should trust the ber values to end
with \0, for that matter.
Finally, libldap/tls.c does not check if ber_decode_oid() fails.