Bug 1179598 – VUL-1: CVE-2020-29534: kernel-source: io_uring takes a non-refcounted reference to the files_struct of the process that submitted a request, causing execve() to incorrectly optimize

Bug 1179598 - (CVE-2020-29534) VUL-1: CVE-2020-29534: kernel-source: io_uring takes a non-refcounted reference to the files_struct of the process that submitted a request, causing execve() to incorrectly optimize

(CVE-2020-29534)
Summary:	VUL-1: CVE-2020-29534: kernel-source: io_uring takes a non-refcounted referen...

Status:	RESOLVED FIXED

Classification:	Novell Products
Product:	SUSE Security Incidents
Classification:	Novell Products
Component:	Incidents
Version:	unspecified
Hardware:	Other Other

Priority:	P4 - Low Severity: Minor
Target Milestone:	---
Assigned To:	Security Team bot
QA Contact:	Security Team bot

URL:	https://smash.suse.de/issue/272707/
Whiteboard:	CVSSv3.1:SUSE:CVE-2020-29534:6.2:(AV:...
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Create test case

Clone This Bug

Reported:	2020-12-04 10:57 UTC by Robert Frohl
Modified:	2022-06-09 10:56 UTC (History)
CC List:	7 users (show)

See Also:
Found By:	Security Response Team
Services Priority:
Business Priority:
Blocker:	---
Marketing QA Status:	---
IT Deployment:	---

Attachments
Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.

Description Robert Frohl 2020-12-04 10:57:06 UTC

CVE-2020-29534

An issue was discovered in the Linux kernel before 5.9.3. io_uring takes a
non-refcounted reference to the files_struct of the process that submitted a
request, causing execve() to incorrectly optimize unshare_fd(), aka
CID-0f2122045b94.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-29534
https://bugs.chromium.org/p/project-zero/issues/detail?id=2089
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-29534
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.9.3
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0f2122045b946241a9e549c2a76cea54fa58a7ff

Comment 1 Robert Frohl 2020-12-04 10:57:59 UTC

tracking as affected:

- SUSE:SLE-15-SP2:Update/kernel-source
- SUSE:SLE-15-SP3:Update/kernel-source

Comment 3 Marcus Meissner 2020-12-07 07:47:12 UTC

can you judge the impact of this? could this be a reference count based use after free thing or a denial of service due to loops?

Comment 6 Jan Kara 2020-12-08 12:00:48 UTC

Normally, Goldwyn's team should be taking care of io_uring. But let me take a look...

So the fix commit 0f2122045b "io_uring: don't rely on weak ->files references" is marked as 5.5+ and indeed as far as I'm looking into io_uring sources the problem has been introduced by fcb323cc53 "io_uring: io_uring: add support for async work inheriting files" which went to 5.5-rc1. We don't have that commit in any of our trees besides "master" so I don't think there's anything to do from our side.

Reassigning back to security team.

Comment 7 Carlos López 2022-06-09 10:56:22 UTC

Done, closing.