From 0e8af2178cb86033d30c2e468b46e42af8af20d9 Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Fri, 7 Jun 2013 00:07:27 +0800 Subject: [PATCH] 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 Acked-by: Minchan Kim [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings [wyj: Backported to 3.4: adjust context] Signed-off-by: Yijing Wang Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zram/zram_sysfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c index 826653f..01f9a79 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); } -- 2.7.4