[PATCH v2 1/3] crypto: atmel-sha204a - fix memory leak at non-blocking RNG work_data
From: Lothar Rubusch <hidden>
Date: 2026-03-31 08:21:19
Also in:
linux-crypto, lkml
Subsystem:
crypto api, microchip atsha204a driver, the rest · Maintainers:
Herbert Xu, "David S. Miller", Thorsten Blum, Linus Torvalds
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 number generator")
Signed-off-by: Lothar Rubusch <redacted>
---
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_work_data *work_data, struct atmel_i2c_client_priv *i2c_priv = work_data->ctx; struct hwrng *rng = areq; - if (status) + if (status) { dev_warn_ratelimited(&i2c_priv->client->dev, "i2c transaction failed (%d)\n", status); + kfree(work_data); + rng->priv = 0; + atomic_dec(&i2c_priv->tfm_count); + return; + } rng->priv = (unsigned long)work_data; - atomic_dec(&i2c_priv->tfm_count); } + static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data, size_t max) {
@@ -41,31 +46,36 @@ static int atmel_sha204a_rng_read_nonblocking(struct hwrng *rng, void *data, i2c_priv = container_of(rng, struct atmel_i2c_client_priv, hwrng); - /* 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 = (struct atmel_i2c_work_data *)rng->priv; max = min(sizeof(work_data->cmd.data), max); memcpy(data, &work_data->cmd.data, max); - rng->priv = 0; - } else { - work_data = kmalloc_obj(*work_data, GFP_ATOMIC); - if (!work_data) { - atomic_dec(&i2c_priv->tfm_count); - return -ENOMEM; - } - work_data->ctx = i2c_priv; - work_data->client = i2c_priv->client; - max = 0; + /* Now, free memory */ + kfree(work_data); + rng->priv = 0; + atomic_dec(&i2c_priv->tfm_count); + return max; } + /* 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 = kmalloc_obj(*work_data, GFP_ATOMIC); + if (!work_data) + return -ENOMEM; + + atomic_inc(&i2c_priv->tfm_count); + work_data->ctx = i2c_priv; + work_data->client = i2c_priv->client; + atmel_i2c_init_random_cmd(&work_data->cmd); atmel_i2c_enqueue(work_data, atmel_sha204a_rng_done, rng); - return max; + return 0; } static int atmel_sha204a_rng_read(struct hwrng *rng, void *data, size_t max,
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2.39.5