| From | Ben Hutchings <> | Date | Wed, 24 Jul 2013 15:02:45 +0100 | Subject | [12/85] zram: protect sysfs handler from invalid memory access |
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3.2.49-rc1 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> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/staging/zram/zram_sysfs.c | 2 ++ 1 file changed, 2 insertions(+)
--- 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(struc 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); }
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