Bug 2516851 (CVE-2026-74402)

Summary: CVE-2026-74402 kernel: crypto: atmel-sha204a - fix blocking and non-blocking rng logic
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's `atmel-sha204a` cryptographic hardware random number generator (HWRNG) driver. Improper buffer management in both blocking and non-blocking paths causes the driver to fail in providing valid entropy. This occurs because the buffer is read starting from byte 1, and only a partial amount of random data is fetched from the return message. Consequently, cryptographic operations relying on this hardware random number generator may be weakened due to insufficient randomness.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-15 06:36:47 UTC 
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
Comment 1 gkamathe 2026-08-19 12:15:24 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081509-CVE-2026-74402-32c4@gregkh/T