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[84.74.0.139]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4887ad8d28bsm14542485e9.10.2026.03.31.01.21.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 01:21:17 -0700 (PDT) From: Lothar Rubusch To: herbert@gondor.apana.org.au, davem@davemloft.net, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@tuxon.dev, ardb@kernel.org, linusw@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 v2 1/3] crypto: atmel-sha204a - fix memory leak at non-blocking RNG work_data Date: Tue, 31 Mar 2026 08:21:03 +0000 Message-Id: <20260331082105.697468-2-l.rubusch@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260331082105.697468-1-l.rubusch@gmail.com> References: <20260331082105.697468-1-l.rubusch@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The driver allocated memory for work_data in the non-blocking read path but never free'd it again. After first read-out the memory pointer seemed to be recycled and never was allocated again, due to some errors in the logic, so that the leak was not growing. Add kfree(work_data) in the completion callback on error. then add kfree(work_data) after the data is consumed in the subsequent read call. Finally ensure atomic_dec() is called only after the data has been consumed or an error occurred to prevent race conditions. Fixes: da001fb651b0 ("crypto: atmel-i2c - add support for SHA204A random nu= mber generator") Signed-off-by: Lothar Rubusch --- drivers/crypto/atmel-sha204a.c | 44 +++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 17 deletions(-) diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index 98d1023007e3..1baf4750d311 100644 --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -24,15 +24,20 @@ static void atmel_sha204a_rng_done(struct atmel_i2c_wor= k_data *work_data, struct atmel_i2c_client_priv *i2c_priv =3D work_data->ctx; struct hwrng *rng =3D areq; =20 - if (status) + if (status) { dev_warn_ratelimited(&i2c_priv->client->dev, "i2c transaction failed (%d)\n", status); + kfree(work_data); + rng->priv =3D 0; + atomic_dec(&i2c_priv->tfm_count); + return; + } =20 rng->priv =3D (unsigned long)work_data; - atomic_dec(&i2c_priv->tfm_count); } =20 + static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *dat= a, size_t max) { @@ -41,31 +46,36 @@ static int atmel_sha204a_rng_read_nonblocking(struct hw= rng *rng, void *data, =20 i2c_priv =3D container_of(rng, struct atmel_i2c_client_priv, hwrng); =20 - /* keep maximum 1 asynchronous read in flight at any time */ - if (!atomic_add_unless(&i2c_priv->tfm_count, 1, 1)) - return 0; - + /* Verify if data available from last run */ if (rng->priv) { work_data =3D (struct atmel_i2c_work_data *)rng->priv; max =3D min(sizeof(work_data->cmd.data), max); memcpy(data, &work_data->cmd.data, max); - rng->priv =3D 0; - } else { - work_data =3D kmalloc_obj(*work_data, GFP_ATOMIC); - if (!work_data) { - atomic_dec(&i2c_priv->tfm_count); - return -ENOMEM; - } - work_data->ctx =3D i2c_priv; - work_data->client =3D i2c_priv->client; =20 - max =3D 0; + /* Now, free memory */ + kfree(work_data); + rng->priv =3D 0; + atomic_dec(&i2c_priv->tfm_count); + return max; } =20 + /* When a request is still in-flight but not processed */ + if (atomic_read(&i2c_priv->tfm_count) > 0) + return 0; + + /* Start a new request */ + work_data =3D kmalloc_obj(*work_data, GFP_ATOMIC); + if (!work_data) + return -ENOMEM; + + atomic_inc(&i2c_priv->tfm_count); + work_data->ctx =3D i2c_priv; + work_data->client =3D i2c_priv->client; + atmel_i2c_init_random_cmd(&work_data->cmd); atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); =20 - return max; + return 0; } =20 static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t ma= x, --=20 2.39.5