Bug 1794404 (CVE-2019-19965)

Summary: CVE-2019-19965 kernel: NULL pointer dereference in drivers/scsi/libsas/sas_discover.c because of mishandling of port disconnection during discovery
Product: [Other] Security Response Reporter: Guilherme de Almeida Suckevicz <gsuckevi>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: acaringi, airlied, bhu, blc, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, john.j5live, jonathan, josef, jross, jshortt, jstancek, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, masami256, matt, mchehab, mcressma, mjg59, mlangsdo, nmurray, qzhao, rt-maint, rvrbovsk, steved, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A NULL pointer dereference flaw was found in the Linux kernel’s SCSI disk subsystem. A local user could use this flaw to crash the system, causing a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1812039, 1812040, 1812042, 1812043, 1794405, 1812041    
Bug Blocks: 1794406    

Description Guilherme de Almeida Suckevicz 2020-01-23 14:14:40 UTC
In the Linux kernel through 5.4.6, there is a NULL pointer dereference in drivers/scsi/libsas/sas_discover.c because of mishandling of port disconnection during discovery, related to a PHY down race condition.

Reference and upstream commit:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f70267f379b5e5e11bdc5d72a56bf17e5feed01f

Comment 1 Guilherme de Almeida Suckevicz 2020-01-23 14:15:28 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1794405]

Comment 2 Justin M. Forbes 2020-01-23 19:13:11 UTC
This is fixed for Fedora with the 5.4.9 stable kernel update.

Comment 5 Alex 2020-03-10 17:22:47 UTC
Mitigation:

To mitigate this issue, prevent module libsas from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.