[PATCH v2 1/7] crypto: ti - Use list_first_entry_or_null() in dthe_get_dev()

[T Pratham <t-pratham@ti.com>]

From: Mert Seftali <mertsftl@gmail.com>

dthe_get_dev() fetches a device from the global device list with
list_first_entry() and then checks the result for NULL. However,
list_first_entry() never returns NULL: on an empty list it returns a
bogus pointer computed from the list head. The NULL check is therefore
dead code, and an empty list would be treated as a valid entry and
moved around as if it were a real device.

Use list_first_entry_or_null() so the existing NULL check works as
intended and an empty list is handled gracefully.

[pratham:]
Add null checks on dev_data in callers of dthe_get_dev().

Fixes: 52f641bc63a4 ("crypto: ti - Add driver for DTHE V2 AES Engine (ECB, CBC)")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/r/202606111933.69GGTKxr-lkp@intel.com/
Signed-off-by: Mert Seftali <mertsftl@gmail.com>
Co-developed-by: T Pratham <t-pratham@ti.com>
Signed-off-by: T Pratham <t-pratham@ti.com>
---
 drivers/crypto/ti/dthev2-aes.c    | 12 ++++++++++--
 drivers/crypto/ti/dthev2-common.c |  2 +-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/ti/dthev2-aes.c b/drivers/crypto/ti/dthev2-aes.c
index eb5cd902dfb59..4fdd24ee91637 100644
--- a/drivers/crypto/ti/dthev2-aes.c
+++ b/drivers/crypto/ti/dthev2-aes.c
@@ -112,6 +112,9 @@ static int dthe_cipher_init_tfm(struct crypto_skcipher *tfm)
 	struct dthe_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
 	struct dthe_data *dev_data = dthe_get_dev(ctx);
 
+	if (!dev_data)
+		return -ENODEV;
+
 	ctx->dev_data = dev_data;
 	ctx->keylen = 0;
 
@@ -124,6 +127,9 @@ static int dthe_cipher_init_tfm_fallback(struct crypto_skcipher *tfm)
 	struct dthe_data *dev_data = dthe_get_dev(ctx);
 	const char *alg_name = crypto_tfm_alg_name(crypto_skcipher_tfm(tfm));
 
+	if (!dev_data)
+		return -ENODEV;
+
 	ctx->dev_data = dev_data;
 	ctx->keylen = 0;
 
@@ -571,10 +577,12 @@ static int dthe_aead_init_tfm(struct crypto_aead *tfm)
 {
 	struct dthe_tfm_ctx *ctx = crypto_aead_ctx(tfm);
 	struct dthe_data *dev_data = dthe_get_dev(ctx);
+	const char *alg_name = crypto_tfm_alg_name(crypto_aead_tfm(tfm));
 
-	ctx->dev_data = dev_data;
+	if (!dev_data)
+		return -ENODEV;
 
-	const char *alg_name = crypto_tfm_alg_name(crypto_aead_tfm(tfm));
+	ctx->dev_data = dev_data;
 
 	ctx->aead_fb = crypto_alloc_sync_aead(alg_name, 0,
 					      CRYPTO_ALG_NEED_FALLBACK);
diff --git a/drivers/crypto/ti/dthev2-common.c b/drivers/crypto/ti/dthev2-common.c
index a2ad79bec105a..cc02449382673 100644
--- a/drivers/crypto/ti/dthev2-common.c
+++ b/drivers/crypto/ti/dthev2-common.c
@@ -40,7 +40,7 @@ struct dthe_data *dthe_get_dev(struct dthe_tfm_ctx *ctx)
 		return ctx->dev_data;
 
 	spin_lock_bh(&dthe_dev_list.lock);
-	dev_data = list_first_entry(&dthe_dev_list.dev_list, struct dthe_data, list);
+	dev_data = list_first_entry_or_null(&dthe_dev_list.dev_list, struct dthe_data, list);
 	if (dev_data)
 		list_move_tail(&dev_data->list, &dthe_dev_list.dev_list);
 	spin_unlock_bh(&dthe_dev_list.lock);
-- 
2.34.1