This is a note to let you know that I've just added the patch titled
zram: avoid invalid memory access in zram_exit()
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-avoid-invalid-memory-access-in-zram_exit.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fd162a76f16083157e32fe5f488f39a319b93fad Mon Sep 17 00:00:00 2001
From: Jiang Liu <liuj97@xxxxxxxxx>
Date: Fri, 7 Jun 2013 00:07:22 +0800
Subject: zram: avoid invalid memory access in zram_exit()
From: Jiang Liu <liuj97@xxxxxxxxx>
commit 6030ea9b35971a4200062f010341ab832e878ac9 upstream.
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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/zram/zram_drv.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -841,9 +841,11 @@ 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");
Patches currently in stable-queue which might be from liuj97@xxxxxxxxx are
queue-3.4/zram-avoid-invalid-memory-access-in-zram_exit.patch
queue-3.4/zram-destroy-all-devices-on-error-recovery-path-in-zram_init.patch
queue-3.4/zram-avoid-access-beyond-the-zram-device.patch
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