Re: CVE-2021-47543: perf report: Fix memory leaks around perf_tip()

[Michal Hocko]

As far as I understand this is a bug in perf (userspace tool). This can
occur when running 'perf report' which has a generally short lived
lifespan. Is this really a CVE fix? What is the actual security threat?

Btw. CVE-2021-47545 is another one matcing the same pattern.

On Fri 24-05-24 17:10:03, Greg KH wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> perf report: Fix memory leaks around perf_tip()
> 
> perf_tip() may allocate memory or use a literal, this means memory
> wasn't freed if allocated. Change the API so that literals aren't used.
> 
> At the same time add missing frees for system_path. These issues were
> spotted using leak sanitizer.
> 
> The Linux kernel CVE team has assigned CVE-2021-47543 to this issue.
> 
> 
> Affected and fixed versions
> ===========================
> 
> 	Fixed in 5.4.164 with commit df5990db088d
> 	Fixed in 5.10.84 with commit ff061b5bda73
> 	Fixed in 5.15.7 with commit 71e284dcebec
> 	Fixed in 5.16 with commit d9fc706108c1
> 
> Please see https://www.kernel.org for a full list of currently supported
> kernel versions by the kernel community.
> 
> Unaffected versions might change over time as fixes are backported to
> older supported kernel versions.  The official CVE entry at
> 	https://cve.org/CVERecord/?id=CVE-2021-47543
> will be updated if fixes are backported, please check that for the most
> up to date information about this issue.
> 
> 
> Affected files
> ==============
> 
> The file(s) affected by this issue are:
> 	tools/perf/builtin-report.c
> 	tools/perf/util/util.c
> 	tools/perf/util/util.h
> 
> 
> Mitigation
> ==========
> 
> The Linux kernel CVE team recommends that you update to the latest
> stable kernel version for this, and many other bugfixes.  Individual
> changes are never tested alone, but rather are part of a larger kernel
> release.  Cherry-picking individual commits is not recommended or
> supported by the Linux kernel community at all.  If however, updating to
> the latest release is impossible, the individual changes to resolve this
> issue can be found at these commits:
> 	https://git.kernel.org/stable/c/df5990db088d4c7fea9a2f9b8195a7859e1768c4
> 	https://git.kernel.org/stable/c/ff061b5bda73c4f785b4703eeb0848fd99e5608a
> 	https://git.kernel.org/stable/c/71e284dcebecb9fd204ff11097469cc547723ad1
> 	https://git.kernel.org/stable/c/d9fc706108c15f8bc2d4ccccf8e50f74830fabd9

-- 
Michal Hocko
SUSE Labs