Subject: CVE-2023-52615: hwrng: core - Fix page fault dead lock on mmap-ed hwrng

From: Greg Kroah-Hartman <[email-masked]>

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

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

hwrng: core - Fix page fault dead lock on mmap-ed hwrng

There is a dead-lock in the hwrng device read path.  This triggers
when the user reads from /dev/hwrng into memory also mmap-ed from
/dev/hwrng.  The resulting page fault triggers a recursive read
which then dead-locks.

Fix this by using a stack buffer when calling copy_to_user.

The Linux kernel CVE team has assigned CVE-2023-52615 to this issue.

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

	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 4.19.307 with commit eafd83b92f6c
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 5.4.269 with commit 5030d4c79886
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 5.10.210 with commit c6a8111aacbf
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 5.15.149 with commit 26cc6d7006f9
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 6.1.76 with commit aa8aa16ed9ad
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 6.6.15 with commit ecabe8cd456d
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 6.7.3 with commit 6822a1427178
	Issue introduced in 2.6.33 with commit 9996508b3353 and fixed in 6.8 with commit 78aafb3884f6

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-2023-52615
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:
	drivers/char/hw_random/core.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/eafd83b92f6c044007a3591cbd476bcf90455990
	https://git.kernel.org/stable/c/5030d4c798863ccb266563201b341a099e8cdd48
	https://git.kernel.org/stable/c/c6a8111aacbfe7a8a70f46cc0de8eed00561693c
	https://git.kernel.org/stable/c/26cc6d7006f922df6cc4389248032d955750b2a0
	https://git.kernel.org/stable/c/aa8aa16ed9adf1df05bb339d588cf485a011839e
	https://git.kernel.org/stable/c/ecabe8cd456d3bf81e92c53b074732f3140f170d
	https://git.kernel.org/stable/c/6822a14271786150e178869f1495cc03e74c5029
	https://git.kernel.org/stable/c/78aafb3884f6bc6636efcc1760c891c8500b9922