linux-kernel - Re: [PATCH v2] mtd: maps: pcmciamtd: fix possible sleep-in-atomic-context bugs in pcmciamtd_set

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Date:   Thu, 19 Dec 2019 07:45:51 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     miquel.raynal@...tlin.com, richard@....at, vigneshr@...com,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mtd: maps: pcmciamtd: fix possible
 sleep-in-atomic-context bugs in pcmciamtd_set_vpp()

On Thu, Dec 19, 2019 at 11:20:23AM +0800, Jia-Ju Bai wrote:
> The driver may sleep while holding a spinlock.
> The function call path (from bottom to top) in Linux 4.19 is:
> 
> drivers/pcmcia/pcmcia_resource.c, 312:
> 	mutex_lock in pcmcia_fixup_vpp
> drivers/mtd/maps/pcmciamtd.c, 309:
> 	pcmcia_fixup_vpp in pcmciamtd_set_vpp
> drivers/mtd/maps/pcmciamtd.c, 306:
> 	_raw_spin_lock_irqsave in pcmciamtd_set_vpp
> 
> drivers/pcmcia/pcmcia_resource.c, 312:
> 	mutex_lock in pcmcia_fixup_vpp
> drivers/mtd/maps/pcmciamtd.c, 312:
> 	pcmcia_fixup_vpp in pcmciamtd_set_vpp
> drivers/mtd/maps/pcmciamtd.c, 306:
> 	_raw_spin_lock_irqsave in pcmciamtd_set_vp
> 
> mutex_lock() may sleep at runtime.
> 
> To fix these bugs, the spinlock is replaced with a mutex.
> 
> These bugs are found by a static analysis tool STCheck written by
> myself.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Reviewed-by: Dominik Brodowski <linux@...inikbrodowski.net>

I presume this will go upstream (with CC to stable -- likely applies to all
longterm kernels still maintained) via MTD? Or should I route it via pcmcia?

Thanks,
	Dominik