[RFC PATCH v1 2/8] zram: avoid invalid memory access in zram_exit()

From: Jiang Liu
Date: Mon Jun 03 2013 - 11:46:22 EST


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.

Fix it by holding an extra reference to zram->disk before calling
destroy_device(zram).

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
---
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 e34e3fe..ee6b67d 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");
--
1.8.1.2

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