mtd: maps: pcmciamtd: fix possible sleep-in-atomic-context bugs in pcmciamtd_set_vpp()
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@gmail.com> Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
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@ -294,16 +294,15 @@ static void pcmcia_copy_to(struct map_info *map, unsigned long to, const void *f
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}
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}
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static DEFINE_SPINLOCK(pcmcia_vpp_lock);
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static DEFINE_MUTEX(pcmcia_vpp_lock);
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static int pcmcia_vpp_refcnt;
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static int pcmcia_vpp_refcnt;
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static void pcmciamtd_set_vpp(struct map_info *map, int on)
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static void pcmciamtd_set_vpp(struct map_info *map, int on)
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{
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{
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struct pcmciamtd_dev *dev = (struct pcmciamtd_dev *)map->map_priv_1;
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struct pcmciamtd_dev *dev = (struct pcmciamtd_dev *)map->map_priv_1;
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struct pcmcia_device *link = dev->p_dev;
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struct pcmcia_device *link = dev->p_dev;
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unsigned long flags;
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pr_debug("dev = %p on = %d vpp = %d\n\n", dev, on, dev->vpp);
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pr_debug("dev = %p on = %d vpp = %d\n\n", dev, on, dev->vpp);
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spin_lock_irqsave(&pcmcia_vpp_lock, flags);
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mutex_lock(&pcmcia_vpp_lock);
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if (on) {
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if (on) {
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if (++pcmcia_vpp_refcnt == 1) /* first nested 'on' */
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if (++pcmcia_vpp_refcnt == 1) /* first nested 'on' */
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pcmcia_fixup_vpp(link, dev->vpp);
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pcmcia_fixup_vpp(link, dev->vpp);
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@ -311,7 +310,7 @@ static void pcmciamtd_set_vpp(struct map_info *map, int on)
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if (--pcmcia_vpp_refcnt == 0) /* last nested 'off' */
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if (--pcmcia_vpp_refcnt == 0) /* last nested 'off' */
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pcmcia_fixup_vpp(link, 0);
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pcmcia_fixup_vpp(link, 0);
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}
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}
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spin_unlock_irqrestore(&pcmcia_vpp_lock, flags);
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mutex_unlock(&pcmcia_vpp_lock);
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}
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}
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