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()
Change-Id: I6616ac8f82aab6d03a47f3cfb91d28a825e6e3a6
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>
Git-commit: 2b86ab9cc29fcd435cde9378c3b9ffe8b5c76128
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 44949d2..2a85b95 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -523,7 +523,7 @@
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 @@
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 @@
if (bdev)
fsync_bdev(bdev);
- zram_reset_device(zram);
+ zram_reset_device(zram, true);
return len;
}
@@ -903,10 +904,12 @@
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");