lkml.org 
[lkml]   [2013]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[145/251] zram: avoid invalid memory access in zram_exit()
3.6.11.9-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Jiang Liu <liuj97@gmail.com>

[ Upstream commit 6030ea9b35971a4200062f010341ab832e878ac9 ]

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>
Signed-off-by: Steven Rostedt <rostedt@goodmis.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 6edefde..38a1b44 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -771,9 +771,11 @@ static void __exit zram_exit(void)
for (i = 0; i < num_devices; i++) {
zram = &zram_devices[i];

+ get_disk(zram->disk);
destroy_device(zram);
if (zram->init_done)
zram_reset_device(zram);
+ put_disk(zram->disk);
}

unregister_blkdev(zram_major, "zram");
--
1.7.10.4



\
 
 \ /
  Last update: 2013-09-11 08:01    [W:0.818 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site