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[84.74.0.139]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4909cab0e79sm59295725e9.13.2026.05.29.02.27.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 May 2026 02:27:09 -0700 (PDT) From: Lothar Rubusch To: thorsten.blum@linux.dev, herbert@gondor.apana.org.au, davem@davemloft.net, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@tuxon.dev, tudor.ambarus@linaro.org, krzk+dt@kernel.org Cc: linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, l.rubusch@gmail.com Subject: [PATCH 1/1] crypto: atmel-ecc - fix use after free situation Date: Fri, 29 May 2026 09:27:03 +0000 Message-Id: <20260529092703.33086-1-l.rubusch@gmail.com> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Fixes a possible race condition, when having multiple of such devices attached (identified by sashiko feedback). The Scenario: Thread A (Device 1 Probe): Successfully adds i2c_priv to the global list (Line 324). The lock is released. Thread B (An active crypto request): Concurrently calls atmel_ecc_i2c_client_alloc(). It scans the global list, sees Device 1, and assigns a crypto job to it. Thread A: Moves to line 332. crypto_register_kpp() fails (e.g., out of memory or name clash). Thread A: Enters the error path. It removes Device 1 from the list and frees the i2c_priv memory. Thread B: Is still actively trying to talk to the I2C hardware using the i2c_priv pointer it grabbed in Step 2. The memory is now gone. Result: Kernel crash (Use-After-Free). Fixes: 11105693fa05 ("crypto: atmel-ecc - introduce Microchip / Atmel ECC driver") Signed-off-by: Lothar Rubusch --- drivers/crypto/atmel-ecc.c | 10 ++++++++++ drivers/crypto/atmel-i2c.h | 2 ++ 2 files changed, 12 insertions(+) diff --git a/drivers/crypto/atmel-ecc.c b/drivers/crypto/atmel-ecc.c index 0ca02995a1de..d391fe1462f6 100644 --- a/drivers/crypto/atmel-ecc.c +++ b/drivers/crypto/atmel-ecc.c @@ -218,6 +218,8 @@ static struct i2c_client *atmel_ecc_i2c_client_alloc(void) list_for_each_entry(i2c_priv, &driver_data.i2c_client_list, i2c_client_list_node) { + if (!i2c_priv->ready) + continue; tfm_cnt = atomic_read(&i2c_priv->tfm_count); if (tfm_cnt < min_tfm_cnt) { min_tfm_cnt = tfm_cnt; @@ -322,20 +324,24 @@ static int atmel_ecc_probe(struct i2c_client *client) return ret; i2c_priv = i2c_get_clientdata(client); + i2c_priv->ready = false; spin_lock(&driver_data.i2c_list_lock); list_add_tail(&i2c_priv->i2c_client_list_node, &driver_data.i2c_client_list); + i2c_priv->ready = true; spin_unlock(&driver_data.i2c_list_lock); ret = crypto_register_kpp(&atmel_ecdh_nist_p256); if (ret) { spin_lock(&driver_data.i2c_list_lock); + i2c_priv->ready = false; list_del(&i2c_priv->i2c_client_list_node); spin_unlock(&driver_data.i2c_list_lock); dev_err(&client->dev, "%s alg registration failed\n", atmel_ecdh_nist_p256.base.cra_driver_name); + return ret; } else { dev_info(&client->dev, "atmel ecc algorithms registered in /proc/crypto\n"); } @@ -347,6 +353,10 @@ static void atmel_ecc_remove(struct i2c_client *client) { struct atmel_i2c_client_priv *i2c_priv = i2c_get_clientdata(client); + spin_lock(&driver_data.i2c_list_lock); + i2c_priv->ready = false; + spin_unlock(&driver_data.i2c_list_lock); + /* Return EBUSY if i2c client already allocated. */ if (atomic_read(&i2c_priv->tfm_count)) { /* diff --git a/drivers/crypto/atmel-i2c.h b/drivers/crypto/atmel-i2c.h index 72f04c15682f..e3b12030f9c4 100644 --- a/drivers/crypto/atmel-i2c.h +++ b/drivers/crypto/atmel-i2c.h @@ -129,6 +129,7 @@ struct atmel_ecc_driver_data { * @wake_token_sz : size in bytes of the wake_token * @tfm_count : number of active crypto transformations on i2c client * @hwrng : hold the hardware generated rng + * @ready : hw client is ready to use * * Reads and writes from/to the i2c client are sequential. The first byte * transmitted to the device is treated as the byte size. Any attempt to send @@ -145,6 +146,7 @@ struct atmel_i2c_client_priv { size_t wake_token_sz; atomic_t tfm_count ____cacheline_aligned; struct hwrng hwrng; + bool ready; }; /** base-commit: 5624ea54f3ba5c83d2e5503411a31a8be0278c1e -- 2.53.0