[PATCH] ksmbd: fix use-after-free from async crypto on Qualcomm crypto engine

[Joshua Klinesmith <joshuaklinesmith@gmail.com>]

ksmbd_crypt_message() sets a NULL completion callback on AEAD requests
and does not handle the -EINPROGRESS return code from async hardware
crypto engines like the Qualcomm Crypto Engine (QCE). When QCE returns
-EINPROGRESS, ksmbd treats it as an error and immediately frees the
request while the hardware DMA operation is still in flight. The DMA
completion callback then dereferences freed memory, causing a NULL
pointer crash:

  pc : qce_skcipher_done+0x24/0x174
  lr : vchan_complete+0x230/0x27c
  ...
  el1h_64_irq+0x68/0x6c
  ksmbd_free_work_struct+0x20/0x118 [ksmbd]
  ksmbd_exit_file_cache+0x694/0xa4c [ksmbd]

Use the standard crypto_wait_req() pattern with crypto_req_done() as
the completion callback, matching the approach used by the SMB client
in fs/smb/client/smb2ops.c. This properly handles both synchronous
engines (immediate return) and async engines (-EINPROGRESS followed
by callback notification).

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Link: https://github.com/openwrt/openwrt/issues/21822
Signed-off-by: Joshua Klinesmith <joshuaklinesmith@gmail.com>
---
 fs/smb/server/auth.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c
index af5f40304331..7d0691f7263f 100644
--- a/fs/smb/server/auth.c
+++ b/fs/smb/server/auth.c
@@ -827,6 +827,7 @@ int ksmbd_crypt_message(struct ksmbd_work *work, struct kvec *iov,
 	struct smb2_transform_hdr *tr_hdr = smb_get_msg(iov[0].iov_base);
 	unsigned int assoc_data_len = sizeof(struct smb2_transform_hdr) - 20;
 	int rc;
+	DECLARE_CRYPTO_WAIT(wait);
 	struct scatterlist *sg;
 	u8 sign[SMB2_SIGNATURE_SIZE] = {};
 	u8 key[SMB3_ENC_DEC_KEY_SIZE];
@@ -913,12 +914,12 @@ int ksmbd_crypt_message(struct ksmbd_work *work, struct kvec *iov,
 
 	aead_request_set_crypt(req, sg, sg, crypt_len, iv);
 	aead_request_set_ad(req, assoc_data_len);
-	aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
+	aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
+				  CRYPTO_TFM_REQ_MAY_SLEEP,
+				  crypto_req_done, &wait);
 
-	if (enc)
-		rc = crypto_aead_encrypt(req);
-	else
-		rc = crypto_aead_decrypt(req);
+	rc = crypto_wait_req(enc ? crypto_aead_encrypt(req) :
+			     crypto_aead_decrypt(req), &wait);
 	if (rc)
 		goto free_iv;
 
-- 
2.43.0