From 17ec4cd985780a7e30aa45bb8f272237c12502a4 Mon Sep 17 00:00:00 2001 From: Jerome Marchand Date: Fri, 15 Jan 2016 16:54:48 -0800 Subject: [PATCH] zram: don't call idr_remove() from zram_remove() The use of idr_remove() is forbidden in the callback functions of idr_for_each(). It is therefore unsafe to call idr_remove in zram_remove(). This patch moves the call to idr_remove() from zram_remove() to hot_remove_store(). In the detroy_devices() path, idrs are removed by idr_destroy(). This solves an use-after-free detected by KASan. [akpm@linux-foundation.org: fix coding stype, per Sergey] Signed-off-by: Jerome Marchand Acked-by: Sergey Senozhatsky Cc: Minchan Kim Cc: [4.2+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zram_drv.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 47915d736f8d4f..370c2f76016d68 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1325,7 +1325,6 @@ static int zram_remove(struct zram *zram) pr_info("Removed device: %s\n", zram->disk->disk_name); - idr_remove(&zram_index_idr, zram->disk->first_minor); blk_cleanup_queue(zram->disk->queue); del_gendisk(zram->disk); put_disk(zram->disk); @@ -1367,10 +1366,12 @@ static ssize_t hot_remove_store(struct class *class, mutex_lock(&zram_index_mutex); zram = idr_find(&zram_index_idr, dev_id); - if (zram) + if (zram) { ret = zram_remove(zram); - else + idr_remove(&zram_index_idr, dev_id); + } else { ret = -ENODEV; + } mutex_unlock(&zram_index_mutex); return ret ? ret : count;