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| author | Jiang Liu <liuj97@gmail.com> | 2013-06-07 00:07:22 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-07-27 05:34:06 +0100 |
| commit | fd162a76f16083157e32fe5f488f39a319b93fad (patch) | |
| tree | ae01977f6a5088b3f78b9e7fbbd73542b5e71425 | |
| parent | 4e9169bee6bc9870277539a425c528584212e76c (diff) | |
| download | lwn-fd162a76f16083157e32fe5f488f39a319b93fad.tar.gz lwn-fd162a76f16083157e32fe5f488f39a319b93fad.zip | |
zram: avoid invalid memory access in zram_exit()
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@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/staging/zram/zram_drv.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index 2594a313d258..e87af2914ddc 100644 --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -846,9 +846,11 @@ static void __exit zram_exit(void) for (i = 0; i < zram_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"); |