| Date | Wed, 11 Sep 2013 00:29:32 -0400 | From | Steven Rostedt <> | Subject | [145/251] zram: avoid invalid memory access in zram_exit() |
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3.6.11.9-rc1 stable review patch. If anyone has any objections, please let me know.
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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
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