From 6030ea9b35971a4200062f010341ab832e878ac9 Mon Sep 17 00:00:00 2001
From: Jiang Liu <liuj97@gmail.com>
Date: Fri, 7 Jun 2013 00:07:22 +0800
Subject: [PATCH] zram: avoid invalid memory access in zram_exit()
Memory for zram->disk object may have already been freed after returning
from destroy_device(zram), then it's unsafe for zram_reset_device(zram)
to access zram->disk again.
We can't solve this bug by flipping the order of destroy_device(zram)
and zram_reset_device(zram), that will cause deadlock issues to the
zram sysfs handler.
So fix it by holding an extra reference to zram->disk before calling
destroy_device(zram).
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/staging/zram/zram_drv.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index d628bd30113cf..9057520c0e403 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -727,8 +727,10 @@ 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);
}
unregister_blkdev(zram_major, "zram");
--
GitLab