| From | Luis Henriques <> | Subject | [PATCH 06/98] zram: protect sysfs handler from invalid memory access | Date | Thu, 11 Jul 2013 15:23:36 +0100 |
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3.5.7.17 -stable review patch. If anyone has any objections, please let me know.
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From: Jiang Liu <liuj97@gmail.com>
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> [ luis: backported to 3.5: - protect access to zram->mem_pool instead of zram->meta ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- 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 a7f3771..dbe8907 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 = 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); } -- 1.8.1.2
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