From: Rashika Kheria Date: Wed, 30 Oct 2013 13:06:32 +0000 (+0530) Subject: Staging: zram: Fix access of NULL pointer X-Git-Tag: firefly_0821_release~176^2~5057^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=46a51c80216cb891f271ad021f59009f34677499;p=firefly-linux-kernel-4.4.55.git Staging: zram: Fix access of NULL pointer This patch fixes the bug in reset_store caused by accessing NULL pointer. The bdev gets its value from bdget_disk() which could fail when memory pressure is severe and hence can return NULL because allocation of inode in bdget could fail. Hence, this patch introduces a check for bdev to prevent reference to a NULL pointer in the later part of the code. It also removes unnecessary check of bdev for fsync_bdev(). Cc: stable Acked-by: Jerome Marchand Signed-off-by: Rashika Kheria Acked-by: Minchan Kim Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index b704d06943f5..79ce363b2ea9 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 -ENOMEM; + /* Do not reset an active device! */ if (bdev->bd_holders) return -EBUSY; @@ -660,8 +663,7 @@ static ssize_t reset_store(struct device *dev, return -EINVAL; /* Make sure all pending I/O is finished */ - if (bdev) - fsync_bdev(bdev); + fsync_bdev(bdev); zram_reset_device(zram, true); return len;