[PATCH 6.18 142/198] smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()

Greg Kroah-Hartman
2026-04-20T16:03:38Z

From: Stefan Metzmacher <metze@samba.org>

commit 27b7c3e916218b5eb2ee350211140e961bfc49be upstream.

smbd_send_batch_flush() already calls smbd_free_send_io(),
so we should not call it again after smbd_post_send()
moved it to the batch list.

Reported-by: Ruikai Peng <ruikai@pwno.io>
Closes: https://lore.kernel.org/linux-cifs/CAFD3drNOSJ05y3A+jNXSDxW-2w09KHQ0DivhxQ_pcc7immVVOQ@mail.gmail.com/
Fixes: 21538121efe6 ("smb: client: make use of smbdirect_socket.send_io.bcredits")
Cc: stable@kernel.org
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Ruikai Peng <ruikai@pwno.io>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Cc: security@kernel.org
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Tested-by: Ruikai Peng <ruikai@pwno.io>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/smb/client/smbdirect.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/fs/smb/client/smbdirect.c
+++ b/fs/smb/client/smbdirect.c
@@ -1525,17 +1525,25 @@ static int smbd_post_send_iter(struct sm

rc = smbd_post_send(sc, batch, request);
if (!rc) {
+ /*
+ * From here request is moved to batch
+ * and we should not free it explicitly.
+ */
+
if (batch != &_batch)
return 0;

rc = smbd_send_batch_flush(sc, batch, true);
if (!rc)
return 0;
+
+ goto err_flush;
}

err_dma:
smbd_free_send_io(request);

+err_flush:
err_alloc:
atomic_inc(&sc->send_io.credits.count);
wake_up(&sc->send_io.credits.wait_queue);