linux kernel 2.6.33.13 dccp handle invalid feature options length

2011-06-30 / 2011-07-01
Credit: Dan Rosenberg
Risk: High
Local: No
Remote: Yes
CWE: CWE-189


CVSS Base Score: 7.8/10
Impact Subscore: 6.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: None
Integrity impact: None
Availability impact: Complete

A length of zero (after subtracting two for the type and len fields) for the DCCPO_{CHANGE,CONFIRM}_{L,R} options will cause an underflow due to the subtraction. The subsequent code may read past the end of the options value buffer when parsing. I'm unsure of what the consequences of this might be, but it's probably not good. Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com> Cc: stable@kernel.org --- net/dccp/options.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/net/dccp/options.c b/net/dccp/options.c index f06ffcf..4b2ab65 100644 --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -123,6 +123,8 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R: if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */ break; + if (len == 0) + goto out_invalid_option; rc = dccp_feat_parse_options(sk, dreq, mandatory, opt, *value, value + 1, len - 1); if (rc)

References:

https://bugzilla.redhat.com/show_bug.cgi?id=703011
http://marc.info/?l=linux-kernel&m=130469305815140&w=2
http://marc.info/?l=linux-kernel&m=130468845209036&w=2
http://lists.fedoraproject.org/pipermail/package-announce/2011-June/061366.html
http://www.securitytracker.com/id?1025592
http://www.securityfocus.2000com/bid/47769
http://www.kernel.org/pub/linux/kernel/v2.6/longterm/v2.6.33/ChangeLog-2.6.33.14
http://secunia.com/advisories/44932


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