From e1c3e37d2c1da620040ada44a92bdb18c4e77dd8 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 Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- 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 0ea8ed296a9db..1fae1e9ae82cd 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); } -- 2.47.3