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Bug 1360354 - Potential null pointer dereference in proto_find_num()
Summary: Potential null pointer dereference in proto_find_num()
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: nftables
Version: 7.3
Hardware: Unspecified
OS: Unspecified
low
low
Target Milestone: rc
: ---
Assignee: Timothy Redaelli
QA Contact: Karel Volný
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-07-26 13:32 UTC by Phil Sutter
Modified: 2017-08-01 18:56 UTC (History)
5 users (show)

Fixed In Version: nftables-0.6-4.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-08-01 18:56:07 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2017:2047 0 normal SHIPPED_LIVE nftables bug fix and enhancement update 2017-08-01 18:13:06 UTC

Description Phil Sutter 2016-07-26 13:32:06 UTC 
As reported by covscan:

 4. nftables-0.6/src/evaluate.c:2016: var_compare_op: Comparing "base" to null implies that "base" might be null.
8. nftables-0.6/src/evaluate.c:2021: var_deref_model: Passing null pointer "base" to "proto_find_num", which dereferences it.
10. nftables-0.6/src/proto.c:79:3: deref_parm: Directly dereferencing parameter "base".
#    77|   
#    78|   	for (i = 0; i < array_size(base->protocols); i++) {
#    79|-> 		if (base->protocols[i].desc == desc)
#    80|   			return base->protocols[i].num;
#    81|   	}


I am not sure if this is valid, it seems like 'base' being NULL is a very special case. Though I couldn't yet verify it's sane either, so better keep this on my todo.
Comment 1 Phil Sutter 2016-09-08 13:32:08 UTC 
Fixed upstream, need to backport this commit:

commit 7241af302bbe56908fa87b17799048bfe884e35f
Author: Phil Sutter <phil>
Date:   Tue Aug 30 19:39:51 2016 +0200

    evaluate: reject: Have a generic fix for missing network context
    
    Commit 17b495957b29e ("evaluate: reject: fix crash if we have transport
    protocol conflict from inet") took care of a crash when using inet or
    bridge families, but since then netdev family has been added which also
    does not implicitly define the network context. Therefore the crash can
    be reproduced again using the following example:
    
    nft add rule netdev filter e1000-ingress \
                meta l4proto udp reject with tcp reset
    
    In order to fix this in a more generic way, have stmt_evaluate_reset()
    fall back to the generic proto_inet_service irrespective of the actual
    proto context.
    
    Signed-off-by: Phil Sutter <phil>
    Signed-off-by: Pablo Neira Ayuso <pablo>
Comment 2 Timothy Redaelli 2017-02-24 11:00:03 UTC 
Backported 7241af302bbe56908fa87b17799048bfe884e35f
Comment 7 errata-xmlrpc 2017-08-01 18:56:07 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2017:2047
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