| Message ID | 20191219032023.7177-1-baijiaju1990@gmail.com |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mtd: maps: pcmciamtd: fix possible sleep-in-atomic-context bugs in pcmciamtd_set_vpp() | expand |
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@gmail.com> Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.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
diff --git a/drivers/mtd/maps/pcmciamtd.c b/drivers/mtd/maps/pcmciamtd.c index 70bb403f69f7..2ac79e1cedd9 100644 --- a/drivers/mtd/maps/pcmciamtd.c +++ b/drivers/mtd/maps/pcmciamtd.c @@ -294,16 +294,15 @@ static void pcmcia_copy_to(struct map_info *map, unsigned long to, const void *f } -static DEFINE_SPINLOCK(pcmcia_vpp_lock); +static DEFINE_MUTEX(pcmcia_vpp_lock); static int pcmcia_vpp_refcnt; static void pcmciamtd_set_vpp(struct map_info *map, int on) { struct pcmciamtd_dev *dev = (struct pcmciamtd_dev *)map->map_priv_1; struct pcmcia_device *link = dev->p_dev; - unsigned long flags; pr_debug("dev = %p on = %d vpp = %d\n\n", dev, on, dev->vpp); - spin_lock_irqsave(&pcmcia_vpp_lock, flags); + mutex_lock(&pcmcia_vpp_lock); if (on) { if (++pcmcia_vpp_refcnt == 1) /* first nested 'on' */ pcmcia_fixup_vpp(link, dev->vpp); @@ -311,7 +310,7 @@ static void pcmciamtd_set_vpp(struct map_info *map, int on) if (--pcmcia_vpp_refcnt == 0) /* last nested 'off' */ pcmcia_fixup_vpp(link, 0); } - spin_unlock_irqrestore(&pcmcia_vpp_lock, flags); + mutex_unlock(&pcmcia_vpp_lock); }
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> --- v2: * Change the spinlock to a mutex. Thank Dominik for good advice. --- drivers/mtd/maps/pcmciamtd.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)