Patch "null_blk: fix dev->badblocks leak" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

    null_blk: fix dev->badblocks leak

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
null_blk-fix-dev-badblocks-leak.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Disseldorp <[email protected]>
Date: Wed, 8 Nov 2017 17:29:44 +0100
Subject: null_blk: fix dev->badblocks leak

From: David Disseldorp <[email protected]>

[ Upstream commit 1addb798e93893d33c8dfab743cd44f09fd7719a ]

null_alloc_dev() allocates memory for dev->badblocks, but cleanup currently only occurs in the configfs release codepath, missing a number of other places.

This bug was found running the blktests block/010 test, alongside kmemleak:

rapido1:/blktests# ./check block/010
...
rapido1:/blktests# echo scan > /sys/kernel/debug/kmemleak
[  306.966708] kmemleak: 32 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
rapido1:/blktests# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff88001f86d000 (size 4096):
  comm "modprobe", pid 231, jiffies 4294892415 (age 318.252s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff814b0379>] kmemleak_alloc+0x49/0xa0
    [<ffffffff810f180f>] kmem_cache_alloc+0x9f/0xe0
    [<ffffffff8124e45f>] badblocks_init+0x2f/0x60
    [<ffffffffa0019fae>] 0xffffffffa0019fae
    [<ffffffffa0021273>] nullb_device_badblocks_store+0x63/0x130 [null_blk]
    [<ffffffff810004cd>] do_one_initcall+0x3d/0x170
    [<ffffffff8109fe0d>] do_init_module+0x56/0x1e9
    [<ffffffff8109ebd7>] load_module+0x1c47/0x26a0
    [<ffffffff8109f819>] SyS_finit_module+0xa9/0xd0
    [<ffffffff814b4f60>] entry_SYSCALL_64_fastpath+0x13/0x94

---
 drivers/block/null_blk.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -467,7 +467,6 @@ static void nullb_device_release(struct
 {
 	struct nullb_device *dev = to_nullb_device(item);
 
-	badblocks_exit(&dev->badblocks);
 	null_free_device_storage(dev, false);
 	null_free_dev(dev);
 }

@@ -578,6 +577,10 @@ static struct nullb_device *null_alloc_d
 
 static void null_free_dev(struct nullb_device *dev)
 {
+	if (!dev)
+		return;
+
+	badblocks_exit(&dev->badblocks);
 	kfree(dev);
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/null_blk-fix-dev-badblocks-leak.patch