All of lore.kernel.org
 help / color / mirror / Atom feed
* FAILED: patch "[PATCH] crypto: atmel-sha204a - drop hwrng quality reduction for" failed to apply to 5.10-stable tree
@ 2026-07-15 10:10 gregkh
  2026-07-20 15:48 ` [PATCH 5.10.y 1/3] crypto: atmel-sha204a - Mark OF related data as maybe unused Sasha Levin
  0 siblings, 1 reply; 4+ messages in thread
From: gregkh @ 2026-07-15 10:10 UTC (permalink / raw)
  To: thorsten.blum, ardb, herbert; +Cc: stable


The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x ea5e57cc97185329dcc5ebdcaae7e1500bf0ad0b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026071514-kindling-fried-4b7e@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ea5e57cc97185329dcc5ebdcaae7e1500bf0ad0b Mon Sep 17 00:00:00 2001
From: Thorsten Blum <thorsten.blum@linux.dev>
Date: Tue, 28 Apr 2026 12:14:32 +0200
Subject: [PATCH] crypto: atmel-sha204a - drop hwrng quality reduction for
 ATSHA204A

Commit 8006aff15516 ("crypto: atmel-sha204a - Set hwrng quality to
lowest possible") reduced the hwrng quality to 1 based on a review by
Bill Cox [1]. However, despite its title, the review only tested the
ATSHA204, not the ATSHA204A.

In the same thread, Atmel engineer Landon Cox wrote "this behavior has
been eliminated entirely"[2] in the ATSHA204A and "this problem does not
affect the ATECC108 or the ATECC108A (or the ATSHA204A)"[3].

According to the official ATSHA204A datasheet [4], the device contains a
high-quality hardware RNG that combines its output with an internal seed
value stored in EEPROM or SRAM to generate random numbers. The device
also implements all security functions using SHA-256, and the driver
uses the chip's Random command in seed-update mode.

Keep 'quality = 1' for ATSHA204, but drop the explicit hwrng quality
reduction for ATSHA204A and fall back to the hwrng core default.

[1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html
[2] https://www.metzdowd.com/pipermail/cryptography/2014-December/023852.html
[3] https://www.metzdowd.com/pipermail/cryptography/2014-December/023886.html
[4] https://ww1.microchip.com/downloads/en/DeviceDoc/ATSHA204A-Data-Sheet-40002025A.pdf

Fixes: 8006aff15516 ("crypto: atmel-sha204a - Set hwrng quality to lowest possible")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c
index 5699bb532325..ed7d69bf6890 100644
--- a/drivers/crypto/atmel-sha204a.c
+++ b/drivers/crypto/atmel-sha204a.c
@@ -19,6 +19,12 @@
 #include <linux/workqueue.h>
 #include "atmel-i2c.h"
 
+/*
+ * According to review by Bill Cox [1], the ATSHA204 has very low entropy.
+ * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html
+ */
+static const unsigned short atsha204_quality = 1;
+
 static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data,
 				   void *areq, int status)
 {
@@ -158,6 +164,7 @@ static const struct attribute_group atmel_sha204a_groups = {
 static int atmel_sha204a_probe(struct i2c_client *client)
 {
 	struct atmel_i2c_client_priv *i2c_priv;
+	const unsigned short *quality;
 	int ret;
 
 	ret = atmel_i2c_probe(client);
@@ -171,11 +178,9 @@ static int atmel_sha204a_probe(struct i2c_client *client)
 	i2c_priv->hwrng.name = dev_name(&client->dev);
 	i2c_priv->hwrng.read = atmel_sha204a_rng_read;
 
-	/*
-	 * According to review by Bill Cox [1], this HWRNG has very low entropy.
-	 * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html
-	 */
-	i2c_priv->hwrng.quality = 1;
+	quality = i2c_get_match_data(client);
+	if (quality)
+		i2c_priv->hwrng.quality = *quality;
 
 	ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng);
 	if (ret)
@@ -203,14 +208,14 @@ static void atmel_sha204a_remove(struct i2c_client *client)
 }
 
 static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
-	{ .compatible = "atmel,atsha204", },
+	{ .compatible = "atmel,atsha204", .data = &atsha204_quality },
 	{ .compatible = "atmel,atsha204a", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids);
 
 static const struct i2c_device_id atmel_sha204a_id[] = {
-	{ "atsha204" },
+	{ "atsha204", (kernel_ulong_t)&atsha204_quality },
 	{ "atsha204a" },
 	{ /* sentinel */ }
 };


^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-07-20 15:48 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-07-15 10:10 FAILED: patch "[PATCH] crypto: atmel-sha204a - drop hwrng quality reduction for" failed to apply to 5.10-stable tree gregkh
2026-07-20 15:48 ` [PATCH 5.10.y 1/3] crypto: atmel-sha204a - Mark OF related data as maybe unused Sasha Levin
2026-07-20 15:48   ` [PATCH 5.10.y 2/3] crypto: atmel - Drop explicit initialization of struct i2c_device_id::driver_data to 0 Sasha Levin
2026-07-20 15:48   ` [PATCH 5.10.y 3/3] crypto: atmel-sha204a - drop hwrng quality reduction for ATSHA204A Sasha Levin

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.