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| author | Jiang Liu <liuj97@gmail.com> | 2013-06-07 00:07:27 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-06-16 13:45:45 -0700 |
| commit | 0e8af2178cb86033d30c2e468b46e42af8af20d9 (patch) | |
| tree | c0768f6d0222d33669754b62386d21bc0e190363 | |
| parent | 480ed1ba70b1cb6977451763a28a658844d59360 (diff) | |
| download | lwn-0e8af2178cb86033d30c2e468b46e42af8af20d9.tar.gz lwn-0e8af2178cb86033d30c2e468b46e42af8af20d9.zip | |
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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[wyj: Backported to 3.4: adjust context]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 826653fff70e..01f9a79aad43 100644 --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -188,10 +188,12 @@ 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 = zs_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); } |