Bug 1629636 (CVE-2018-14641)

Summary:	CVE-2018-14641 kernel: a bug in ip_frag_reasm() can cause a crash in ip_do_fragment()
Product:	[Other] Security Response	Reporter:	Vladis Dronov <vdronov>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	abhgupta, airlied, aquini, bhu, blc, bskeggs, dbaker, dhoward, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, john.j5live, jokerman, jonathan, josef, jross, jstancek, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, plougher, rt-maint, rvrbovsk, security-response-team, skozina, steved, sthangav, trankin, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-10 10:37:53 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1616059, 1629657, 1629658, 1630276, 1630279
Bug Blocks:	1629630

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