CVE-2021-47002: SUNRPC: Fix null pointer dereference in svc_rqst_free()

CVE-2021-47002: SUNRPC: Fix null pointer dereference in svc_rqst_free()

[Greg Kroah-Hartman]

From: gregkh@kernel.org

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

SUNRPC: Fix null pointer dereference in svc_rqst_free()

When alloc_pages_node() returns null in svc_rqst_alloc(), the
null rq_scratch_page pointer will be dereferenced when calling
put_page() in svc_rqst_free(). Fix it by adding a null check.

Addresses-Coverity: ("Dereference after null check")

The Linux kernel CVE team has assigned CVE-2021-47002 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.11 with commit 5191955d6fc6 and fixed in 5.11.22 with commit 1e10f58f1c9a
	Issue introduced in 5.11 with commit 5191955d6fc6 and fixed in 5.12.5 with commit c664aaec9aee
	Issue introduced in 5.11 with commit 5191955d6fc6 and fixed in 5.13 with commit b9f83ffaa0c0

Please see https://www.kernel.org or 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-2021-47002
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:
	net/sunrpc/svc.c


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/1e10f58f1c9a6b667b045513c7a4e6111c24fe7c
	https://git.kernel.org/stable/c/c664aaec9aee544538a78ba4893a44bc73a6d742
	https://git.kernel.org/stable/c/b9f83ffaa0c096b4c832a43964fe6bff3acffe10