CVE-2026-74402: crypto: atmel-sha204a - fix blocking and non-blocking rng logic

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

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

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

crypto: atmel-sha204a - fix blocking and non-blocking rng logic

The blocking and non-blocking paths were failing to provide valid entropy
due to improper buffer management. Reading the buffer starting from byte 1,
only fetch the 32 bytes of random data from the return message.

Tested on an Atmel SHA204A device.

Before (here for blocking), tests showed repeatedly reading reduced bytes.
$ head -c 32 /dev/hwrng | hexdump -C
00000000  02 28 85 b3 47 40 f2 ee  00 00 00 00 00 00 00 00  |.(..G@..........|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020

After, the result will be similar to the following:
$ head -c 32 /dev/hwrng | hexdump -C
00000000  5a fc 3f 13 14 68 fe 06  68 0a bd 04 83 6e 09 69  |Z.?..h..h....n.i|
00000010  75 ff cf 87 10 84 3b c9  c1 df ae eb 45 53 4c c3  |u.....;.....ESL.|
00000020

The Linux kernel CVE team has assigned CVE-2026-74402 to this issue.


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

	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 5.10.261 with commit 76269a91fd9560c5f03c3e59421a0329e39a6661
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 5.15.212 with commit 9039bb4f238474379221fc933c34f19f0cba501b
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 6.1.178 with commit d4aa6141ff03ec82eed6fcef814300fb855ce5d8
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 6.6.145 with commit e833e865e4944ba75120db534bd931db6cf677d3
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 6.12.97 with commit 2fa302bbc62dec7cb6339c9494e0e3f2f884afeb
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 6.18.40 with commit aac63bbea8fd5a34f1a4305cb73369068f952d32
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 7.1.5 with commit 938ae1fb4a8f5db43b62b6206d409efbf317f0d9
	Issue introduced in 5.3 with commit da001fb651b00e1deeaf24767dd691ae8152a4f5 and fixed in 7.2-rc1 with commit 319400fc5ee15db5793aa45f854968141326effc

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-2026-74402
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/crypto/atmel-sha204a.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/76269a91fd9560c5f03c3e59421a0329e39a6661
	https://git.kernel.org/stable/c/9039bb4f238474379221fc933c34f19f0cba501b
	https://git.kernel.org/stable/c/d4aa6141ff03ec82eed6fcef814300fb855ce5d8
	https://git.kernel.org/stable/c/e833e865e4944ba75120db534bd931db6cf677d3
	https://git.kernel.org/stable/c/2fa302bbc62dec7cb6339c9494e0e3f2f884afeb
	https://git.kernel.org/stable/c/aac63bbea8fd5a34f1a4305cb73369068f952d32
	https://git.kernel.org/stable/c/938ae1fb4a8f5db43b62b6206d409efbf317f0d9
	https://git.kernel.org/stable/c/319400fc5ee15db5793aa45f854968141326effc