linux-kernel - [char-misc-next v3] mei: use kvmalloc for read buffer

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Message-ID: <20241015123157.2337026-1-alexander.usyskin@intel.com>
Date: Tue, 15 Oct 2024 15:31:57 +0300
From: Alexander Usyskin <alexander.usyskin@...el.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Oren Weil <oren.jer.weil@...el.com>,
	Tomas Winkler <tomasw@...il.com>,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	Alexander Usyskin <alexander.usyskin@...el.com>,
	Rohit Agarwal <rohiagar@...omium.org>,
	Brian Geffon <bgeffon@...gle.com>
Subject: [char-misc-next v3] mei: use kvmalloc for read buffer

Read buffer is allocated according to max message size, reported by
the firmware and may reach 64K in systems with pxp client.
Contiguous 64k allocation may fail under memory pressure.
Read buffer is used as in-driver message storage and not required
to be contiguous.
Use kvmalloc to allow kernel to allocate non-contiguous memory.

Fixes: 3030dc056459 ("mei: add wrapper for queuing control commands.")
Reported-by: Rohit Agarwal <rohiagar@...omium.org>
Closes: https://lore.kernel.org/all/20240813084542.2921300-1-rohiagar@chromium.org/
Tested-by: Brian Geffon <bgeffon@...gle.com>
Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
---

Changes since V2:
 - add Fixes and CC:stable

Changes since V1:
 - add Tested-by and Reported-by

 drivers/misc/mei/client.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index 9d090fa07516..be011cef12e5 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -321,7 +321,7 @@ void mei_io_cb_free(struct mei_cl_cb *cb)
 		return;
 
 	list_del(&cb->list);
-	kfree(cb->buf.data);
+	kvfree(cb->buf.data);
 	kfree(cb->ext_hdr);
 	kfree(cb);
 }
@@ -497,7 +497,7 @@ struct mei_cl_cb *mei_cl_alloc_cb(struct mei_cl *cl, size_t length,
 	if (length == 0)
 		return cb;
 
-	cb->buf.data = kmalloc(roundup(length, MEI_SLOT_SIZE), GFP_KERNEL);
+	cb->buf.data = kvmalloc(roundup(length, MEI_SLOT_SIZE), GFP_KERNEL);
 	if (!cb->buf.data) {
 		mei_io_cb_free(cb);
 		return NULL;
-- 
2.43.0