Messages in this thread | | | Date | Mon, 28 Oct 2013 23:09:36 +0800 | Subject | Re: [PATCH v6 1/3] Staging: zram: Fix access of NULL pointer | From | Weijie Yang <> |
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On Mon, Oct 28, 2013 at 10:33 PM, Rashika Kheria <rashika.kheria@gmail.com> wrote: > > > > On Mon, Oct 28, 2013 at 7:15 PM, Weijie Yang <weijie.yang.kh@gmail.com> > wrote: >> >> On Mon, Oct 28, 2013 at 8:21 PM, Rashika Kheria >> <rashika.kheria@gmail.com> wrote: >> > This patch fixes the bug in reset_store caused by accessing NULL >> > pointer. >> > Hence, It introduces a check for bdev. It also removes unnecessary check >> > of bdev for fsync_bdev(). >> > >> > Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com> >> > --- >> > >> > This revision fixes the following issues of the previous revision- >> > Seperating patches into Bug fix and Smatch fix >> > >> > drivers/staging/zram/zram_drv.c | 6 ++++-- >> > 1 file changed, 4 insertions(+), 2 deletions(-) >> > >> > diff --git a/drivers/staging/zram/zram_drv.c >> > b/drivers/staging/zram/zram_drv.c >> > index 2c4ed52..d640a8f 100644 >> > --- a/drivers/staging/zram/zram_drv.c >> > +++ b/drivers/staging/zram/zram_drv.c >> > @@ -648,6 +648,9 @@ static ssize_t reset_store(struct device *dev, >> > zram = dev_to_zram(dev); >> > bdev = bdget_disk(zram->disk, 0); >> > >> > + if (!bdev) >> > + return -EBUSY; >> > + >> >> I am not sure how does it happen. Would you please make it clear to me? >> > > Hi Weijie, > > The bdev gets its value from bdget_disk() which could fail when memory is > less available and hence bdev can be NULL. > > If this check is not introduced then we might reference NULL pointer in the > later part of the code.
I see. Thanks!
> I hope I am clear. > > Thanks, > > -- > Rashika Kheria > B.Tech CSE > IIIT Hyderabad
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