From: Jiang Liu <liuj97@xxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
[wyj: Backported to 3.4: adjust context]
Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
---
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 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);
}
--
1.7.1
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