Bug 1629636 (CVE-2018-14641) - CVE-2018-14641 kernel: a bug in ip_frag_reasm() can cause a crash in ip_do_fragment()
Summary: CVE-2018-14641 kernel: a bug in ip_frag_reasm() can cause a crash in ip_do_fr...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2018-14641
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1616059 1629657 1629658 1630276 1630279
Blocks: 1629630
TreeView+ depends on / blocked
 
Reported: 2018-09-17 08:40 UTC by Vladis Dronov
Modified: 2021-02-16 23:02 UTC (History)
47 users (show)

Fixed In Version: kernel 4.19-rc4
Doc Type: If docs needed, set a value
Doc Text:
A security flaw was found in the ip_frag_reasm() function in net/ipv4/ip_fragment.c in the Linux kernel which can cause a later system crash in ip_do_fragment(). With certain non-default, but non-rare, configuration of a victim host, an attacker can trigger this crash remotely, thus leading to a remote denial of service.
Clone Of:
Environment:
Last Closed: 2019-06-10 10:37:53 UTC
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2018:2948 0 None None None 2018-10-30 09:05:30 UTC

Description Vladis Dronov 2018-09-17 08:40:17 UTC 
A security flaw was found in the ip_frag_reasm() function in net/ipv4/ip_fragment.c in the Linux kernel which can cause a later system crash in ip_do_fragment(). With certain non-default but non-rare configuration of a victim host an attacker can trigger this crash remotely, thus leading to a remote denial-of-service.

References:

https://seclists.org/oss-sec/2018/q3/248

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5d407b071dc369c26a38398326ee2be53651cfe4
Comment 4 Vladis Dronov 2018-09-17 09:12:34 UTC 
Note:

The fix is the upstream commit 5d407b071dc3 ("ip: frags: fix crash in ip_do_fragment()") and it is fixing fa0f527358bd ("ip: use rb trees for IP frag queue."). Namely, the following part of fa0f527358bd which unions sk and ip_defrag_offset fields of struct sk_buff has introduced the vulnerability:

+++ b/include/linux/skbuff.h
@@ -676,13 +676,16 @@ struct sk_buff {
+
+       union {
+               struct sock             *sk;
+               int                     ip_defrag_offset;
+       };

Only Red Hat Enterprise Linux 7 for ARM 64 and Red Hat Enterprise Linux 7 for Power 9 LE (the RHEL-ALT product) has backported this part of fa0f527358bd and so is vulnerable to this flaw. Future Linux kernel updates for this product may address this issue.
Comment 6 Vladis Dronov 2018-09-18 10:05:44 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1630279]
Comment 8 errata-xmlrpc 2018-10-30 09:05:09 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:2948 https://access.redhat.com/errata/RHSA-2018:2948
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