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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 <jmarchan@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: <stable@vger.kernel.org>	[4.2+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jerome Marchand 2016-01-15 16:54:48 -08:00 committed by Linus Torvalds
parent 8749cfea11
commit 17ec4cd985
1 changed files with 4 additions and 3 deletions
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7
drivers/block/zram/zram_drv.c
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@ -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;