Commit 73e6ff71 authored Apr 04, 2019 by Guenter Roeck

hwmon: (f71805f) Use request_muxed_region for Super-IO accesses



Super-IO accesses may fail on a system with no or unmapped LPC bus.

Unable to handle kernel paging request at virtual address ffffffbffee0002e
pgd = ffffffc1d68d4000
[ffffffbffee0002e] *pgd=0000000000000000, *pud=0000000000000000
Internal error: Oops: 94000046 [#1] PREEMPT SMP
Modules linked in: f71805f(+) hwmon
CPU: 3 PID: 1659 Comm: insmod Not tainted 4.5.0+ #88
Hardware name: linux,dummy-virt (DT)
task: ffffffc1f6665400 ti: ffffffc1d6418000 task.ti: ffffffc1d6418000
PC is at f71805f_find+0x6c/0x358 [f71805f]

Also, other drivers may attempt to access the LPC bus at the same time,
resulting in undefined behavior.

Use request_muxed_region() to ensure that IO access on the requested
address space is supported, and to ensure that access by multiple
drivers is synchronized.

Fixes: e53004e2 ("hwmon: New f71805f driver")
Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: John Garry <john.garry@huawei.com>
Cc: John Garry <john.garry@huawei.com>
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

parent df6b8c70

drivers/hwmon/f71805f.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -96,17 +96,23 @@ superio_select(int base, int ld)
		outb(ld, base + 1);
		}

		static inline void
		static inline int
		superio_enter(int base)
		{
		if (!request_muxed_region(base, 2, DRVNAME))
		return -EBUSY;

		outb(0x87, base);
		outb(0x87, base);

		return 0;
		}

		static inline void
		superio_exit(int base)
		{
		outb(0xaa, base);
		release_region(base, 2);
		}

		/*
		@@ -1561,7 +1567,7 @@ exit:
		static int __init f71805f_find(int sioaddr, unsigned short *address,
		struct f71805f_sio_data *sio_data)
		{
		int err = -ENODEV;
		int err;
		u16 devid;

		static const char * const names[] = {
		@@ -1569,8 +1575,11 @@ static int __init f71805f_find(int sioaddr, unsigned short *address,
		"F71872F/FG or F71806F/FG",
		};

		superio_enter(sioaddr);
		err = superio_enter(sioaddr);
		if (err)
		return err;

		err = -ENODEV;
		devid = superio_inw(sioaddr, SIO_REG_MANID);
		if (devid != SIO_FINTEK_ID)
		goto exit;

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