Date: Tue, 5 Apr 2011 11:37:37 -0400 From: Dan Rosenberg <dan.j.rosenberg@...il.com> To: oss-security@...ts.openwall.com Cc: "Steven M. Christey" <coley@...-smtp.mitre.org>, Josh Bressers <bressers@...hat.com>, Eugene Teo <eugene@...hat.com> Subject: Re: CVE request: kernel: multiple issues in ROSE Hi, This breakdown seems to make sense. I'll do my best to break up the issues below. > > Dan, could you confirm that this breakdown makes sense? > > 1) buffer overflows (not validating length is <= the maximum) > 1) When parsing the FAC_NATIONAL_DIGIS facilities field, it's possible for a remote host to provide more digipeaters than expected, resulting in heap corruption. Check against ROSE_MAX_DIGIS to prevent overflows, and abort facilities parsing on failure. It looks like this will be CVE-2011-1493. 2) When parsing the FAC_CCITT_DEST_NSAP and FAC_CCITT_SRC_NSAP facilities fields, a remote host can provide a length of greater than 20, resulting in a stack overflow of the callsign array. > 2) use of negative signed integers in memcpy() and other operations where > conversion creates a large unsigned integer, referred to as > "underflow" > 3) When parsing the FAC_CCITT_DEST_NSAP and FAC_CCITT_SRC_NSAP facilities fields, a remote host can provide a length of less than 10, resulting in an underflow in a memcpy size, causing a kernel panic due to massive heap corruption. Note that 2) and 3) are solved by validating a single length field, so maybe they should be grouped together? The above three issues were all found by me. > 3) any other types of problems that aren't covered by those two? (The > length validation checks don't always have enough context in the source > code). > 4) Ben Hutchings' fixes addressed multiple cases where the ROSE protocol did not ensure that socket data being parsed wasn't being read in from beyond the boundaries of the incoming socket buffer. For example, a received packet might provide a length field longer than the amount of remaining data in the socket buffer. Looking at the patch, it doesn't appear that any memory corruption would be caused by this, since the out-of-bounds data is still validated by the parsing code. I'd say the impact is likely limited to possible information disclosure, if the contents of the out-of-bounds memory could be inferred by the behavior of the protocol during parsing. It's theoretically possible (but very unlikely) that this could cause read accesses to unmapped memory, which would cause a DOS. -Dan > We would need separate CVE's for the issues found by Dan versus the issues > found by Ben Hutchings. > > Arguably, #2 could probably be broken down further, but without enough > source code context in the patches, it's not immediately clear. > > - Steve >
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