diff options
| author | Jiang Liu <liuj97@gmail.com> | 2013-06-07 00:07:27 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-07-27 05:34:08 +0100 |
| commit | e1c3e37d2c1da620040ada44a92bdb18c4e77dd8 (patch) | |
| tree | d685be7085b2fbb4009346c69f68f9428a591ecb /drivers | |
| parent | 624d1705fa1d6e4c647ca5859ecd921748bd85bf (diff) | |
zram: protect sysfs handler from invalid memory access
commit 5863e10b441e7ea4b492f930f1be180a97d026f3 upstream.
Use zram->init_lock to protect access to zram->meta, otherwise it
may cause invalid memory access if zram->meta has been freed by
zram_reset_device().
This issue may be triggered by:
Thread 1:
while true; do cat mem_used_total; done
Thread 2:
while true; do echo 8M > disksize; echo 1 > reset; done
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/staging/zram/zram_sysfs.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c index 0ea8ed296a9d..1fae1e9ae82c 100644 --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -186,10 +186,12 @@ static ssize_t mem_used_total_show(struct device *dev, u64 val = 0; struct zram *zram = dev_to_zram(dev); + down_read(&zram->init_lock); if (zram->init_done) { val = xv_get_total_size_bytes(zram->mem_pool) + ((u64)(zram->stats.pages_expand) << PAGE_SHIFT); } + up_read(&zram->init_lock); return sprintf(buf, "%llu\n", val); } |