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zram: fix invalid memory access 

[1] tried to fix invalid memory access on zram->disk but it didn't
fix properly because get_disk failed during module exit path.

Actually, we don't need to reset zram->disk's capacity to zero
in module exit path so that this patch introduces new argument
"reset_capacity" on zram_reset_divice and it only reset it when
reset_store is called.

[1] 6030ea9b,  zram: avoid invalid memory access in zram_exit()

Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Minchan Kim 2013-08-12 15:13:55 +09:00 committed by Greg Kroah-Hartman
parent 725acc861b
commit 2b86ab9cc2
1 changed files with 9 additions and 6 deletions
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15
drivers/staging/zram/zram_drv.c
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@ -523,7 +523,7 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
return ret;
}
static void zram_reset_device(struct zram *zram)
static void zram_reset_device(struct zram *zram, bool reset_capacity)
{
size_t index;
struct zram_meta *meta;
@ -552,7 +552,8 @@ static void zram_reset_device(struct zram *zram)
memset(&zram->stats, 0, sizeof(zram->stats));
zram->disksize = 0;
set_capacity(zram->disk, 0);
if (reset_capacity)
set_capacity(zram->disk, 0);
up_write(&zram->init_lock);
}
@ -636,7 +637,7 @@ static ssize_t reset_store(struct device *dev,
if (bdev)
fsync_bdev(bdev);
zram_reset_device(zram);
zram_reset_device(zram, true);
return len;
}
@ -903,10 +904,12 @@ static void __exit zram_exit(void)
for (i = 0; i < num_devices; i++) {
zram = &zram_devices[i];
get_disk(zram->disk);
destroy_device(zram);
zram_reset_device(zram);
put_disk(zram->disk);
/*
* Shouldn't access zram->disk after destroy_device
* because destroy_device already released zram->disk.
*/
zram_reset_device(zram, false);
}
unregister_blkdev(zram_major, "zram");