Commit 56448e78 authored by Andrew Jeffery's avatar Andrew Jeffery
Browse files

soc: aspeed: lpc-snoop: Don't disable channels that aren't enabled 



Mitigate e.g. the following:

    # echo 1e789080.lpc-snoop > /sys/bus/platform/drivers/aspeed-lpc-snoop/unbind
    ...
    [  120.363594] Unable to handle kernel NULL pointer dereference at virtual address 00000004 when write
    [  120.373866] [00000004] *pgd=00000000
    [  120.377910] Internal error: Oops: 805 [#1] SMP ARM
    [  120.383306] CPU: 1 UID: 0 PID: 315 Comm: sh Not tainted 6.15.0-rc1-00009-g926217bc7d7d-dirty #20 NONE
    ...
    [  120.679543] Call trace:
    [  120.679559]  misc_deregister from aspeed_lpc_snoop_remove+0x84/0xac
    [  120.692462]  aspeed_lpc_snoop_remove from platform_remove+0x28/0x38
    [  120.700996]  platform_remove from device_release_driver_internal+0x188/0x200
    ...

Fixes: 9f4f9ae8 ("drivers/misc: add Aspeed LPC snoop driver")
Cc: stable@vger.kernel.org
Cc: Jean Delvare <jdelvare@suse.de>
Acked-by: default avatarJean Delvare <jdelvare@suse.de>
Link: https://patch.msgid.link/20250616-aspeed-lpc-snoop-fixes-v2-2-3cdd59c934d3@codeconstruct.com.au


Signed-off-by: default avatarAndrew Jeffery <andrew@codeconstruct.com.au>
parent 8481d59b

drivers/soc/aspeed/aspeed-lpc-snoop.c

+11 −0
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ struct aspeed_lpc_snoop_model_data { 
};



struct aspeed_lpc_snoop_channel {

	bool enabled;

	struct kfifo		fifo;

	wait_queue_head_t	wq;

	struct miscdevice	miscdev;
@@ -190,6 +191,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 
	const struct aspeed_lpc_snoop_model_data *model_data =

		of_device_get_match_data(dev);



	if (WARN_ON(lpc_snoop->chan[channel].enabled))

		return -EBUSY;



	init_waitqueue_head(&lpc_snoop->chan[channel].wq);

	/* Create FIFO datastructure */

	rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo,
@@ -236,6 +240,8 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 
		regmap_update_bits(lpc_snoop->regmap, HICRB,

				hicrb_en, hicrb_en);



	lpc_snoop->chan[channel].enabled = true;



	return 0;



err_misc_deregister:
@@ -248,6 +254,9 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 
static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,

				     int channel)

{

	if (!lpc_snoop->chan[channel].enabled)

		return;



	switch (channel) {

	case 0:

		regmap_update_bits(lpc_snoop->regmap, HICR5,
@@ -263,6 +272,8 @@ static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 
		return;

	}



	lpc_snoop->chan[channel].enabled = false;

	/* Consider improving safety wrt concurrent reader(s) */

	misc_deregister(&lpc_snoop->chan[channel].miscdev);

	kfifo_free(&lpc_snoop->chan[channel].fifo);

}