From: Rashika Kheria Date: Wed, 30 Oct 2013 13:06:32 +0000 (+0530) Subject: Staging: zram: Fix access of NULL pointer X-Git-Tag: v3.4.92~114 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=70e8fcb681a1f43568778bbb74b7ad2655fa8e74;p=thirdparty%2Fkernel%2Fstable.git Staging: zram: Fix access of NULL pointer commit 46a51c80216cb891f271ad021f59009f34677499 upstream. 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(). Acked-by: Jerome Marchand Signed-off-by: Rashika Kheria Acked-by: Minchan Kim Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings Cc: Jianguo Wu Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c index a7f377175525b..826653fff70ec 100644 --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -95,6 +95,9 @@ 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; @@ -107,8 +110,7 @@ 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); down_write(&zram->init_lock); if (zram->init_done)