| From | Ben Hutchings <> | Date | Sun, 29 Dec 2013 03:08:44 +0100 | Subject | [PATCH 3.2 094/185] Staging: zram: Fix access of NULL pointer |
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3.2.54-rc1 review patch. If anyone has any objections, please let me know.
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From: Rashika Kheria <rashika.kheria@gmail.com>
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 <jmarchan@redhat.com> Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/staging/zram/zram_sysfs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- 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 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 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)
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