> Steve Kiernan wrote: >> I was looking at this patch, but there seems to be an error in it: >> >> unsigned char slc_reply[128]; >> +unsigned char const * const slc_reply_eom = >> &slc_reply[sizeof(slc_reply)]; >> unsigned char *slc_replyp; >> >> Should the value for slc_reply_eom not be this instead? >> >> unsigned char const * const slc_reply_eom = &slc_reply[sizeof(slc_reply) >> - 1]; > > No. > >> Considering the conditionals are the following: >> >> + if (&slc_replyp[6+2] > slc_reply_eom) >> + return; >> >> .. and .. >> >> + /* The end of negotiation command requires 2 bytes. */ >> + if (&slc_replyp[2] > slc_reply_eom) >> + return; >> >> If you don't subtract 1 from the sizeof(slc_reply) or change the >> conditional operators to >=, then you could try to write one byte past >> the end of the buffer. > > The tests are written a bit oddly, but I'm fairly certain that they > are correct. &slc_replyp[6+2] and &slc_replyp[2] are not the > addresses of the last bytes which will be written; rather, they are > the addresses of the byte after the last byte which will be written. > > Taking the second example, if slc_replyp == slc_reply + 126, then we > will have &slc_replyp[2] == slc_reply_eom, but (looking at the code) > the two final bytes will be written into slc_reply[126] and > slc_reply[127]. > > Colin Percival
Actually I've not read the code, but from these email it seems to me that someone could be confused by this code (at least Steve and I); for example refer to the address "&slc_reply[128];" when slc_reply[127] is the last element. I do not want to be offensive in any way, what I want to say is that this code is clear to you (and the person who wrote it) but the next programmer that will reuse the code (because this is a open source) could make a mistake. I think many bugs can derive from code not easy to understand. This is only my opinion. Kind Regards, Roberto _______________________________________________ freebsd-security@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "[EMAIL PROTECTED]"
