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authorJiang Liu <liuj97@gmail.com>2013-06-07 00:07:27 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-16 13:45:45 -0700
commit0e8af2178cb86033d30c2e468b46e42af8af20d9 (patch)
parent480ed1ba70b1cb6977451763a28a658844d59360 (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> [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>
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);