Date: Mon, 11 Apr 2011 22:19:11 -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 Any update on this? -Dan On Tue, Apr 5, 2011 at 11:37 AM, Dan Rosenberg <dan.j.rosenberg@...il.com> wrote: > 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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