Bug 1563069 (CVE-2017-18255)

Summary: CVE-2017-18255 kernel: Integer overflow in events/core.c:perf_cpu_time_max_percent_handler() can allow for denial of service
Product: [Other] Security Response Reporter: Sam Fowler <sfowler>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: airlied, ajax, aquini, bhu, blc, bskeggs, dhoward, esammons, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, john.j5live, jonathan, josef, jross, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, lwang, matt, mchehab, mcressma, mguzik, mjg59, mlangsdo, nmurray, plougher, rt-maint, rvrbovsk, skozina, slawomir, steved, vdronov, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel 4.11 Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the Linux kernel's kernel/events/core.c:perf_cpu_time_max_percent_handler() function. Local privileged users could exploit this flaw to cause a denial of service due to integer overflow or possibly have unspecified other impact.
Story Points: ---
Clone Of: Environment:
Last Closed: 2018-04-04 17:06:39 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 1563071    

Description Sam Fowler 2018-04-03 06:28:21 UTC
The Linux kernel has a vulnerability in the kernel/events/core.c:perf_cpu_time_max_percent_handler() function which local privileged users could exploit to cause a denial of service due to integer overflow or possibly have unspecified other impact.

References:

https://marc.info/?l=linux-kernel&m=148782918310003

An upstream Patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1572e45a924f254d9570093abde46430c3172e3d

Comment 3 Vladis Dronov 2018-04-04 17:03:25 UTC
Notes:

This flaw is exploitable by the privileged user (the real "root") only and not from namespaces:

# ls -l /proc/sys/kernel/perf_cpu_time_max_percent
-rw-r--r-- 1 root root 0 Apr  4 18:52 /proc/sys/kernel/perf_cpu_time_max_percent

$ unshare -U -r
# echo 30 > /proc/sys/kernel/perf_cpu_time_max_percent
-bash: /proc/sys/kernel/perf_cpu_time_max_percent: Permission denied