Patch "block/rnbd-clt: Fix missing a memory free when unloading the module" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    block/rnbd-clt: Fix missing a memory free when unloading the module

to the 5.10-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:
     block-rnbd-clt-fix-missing-a-memory-free-when-unload.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 24a4ecc5239cec18627076a83765b005a6d22e69
Author: Gioh Kim <gi-oh.kim@xxxxxxxxxxxxxxx>
Date:   Mon Apr 19 09:37:15 2021 +0200

    block/rnbd-clt: Fix missing a memory free when unloading the module
    
    [ Upstream commit 12b06533104e802df73c1fbe159437c19933d6c0 ]
    
    When unloading the rnbd-clt module, it does not free a memory
    including the filename of the symbolic link to /sys/block/rnbdX.
    
    It is found by kmemleak as below.
    
    unreferenced object 0xffff9f1a83d3c740 (size 16):
      comm "bash", pid 736, jiffies 4295179665 (age 9841.310s)
      hex dump (first 16 bytes):
        21 64 65 76 21 6e 75 6c 6c 62 30 40 62 6c 61 00  !dev!nullb0@bla.
      backtrace:
        [<0000000039f0c55e>] 0xffffffffc0456c24
        [<000000001aab9513>] kernfs_fop_write+0xcf/0x1c0
        [<00000000db5aa4b3>] vfs_write+0xdb/0x1d0
        [<000000007a2e2207>] ksys_write+0x65/0xe0
        [<00000000055e280a>] do_syscall_64+0x50/0x1b0
        [<00000000c2b51831>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Signed-off-by: Gioh Kim <gi-oh.kim@xxxxxxxxx>
    Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20210419073722.15351-13-gi-oh.kim@xxxxxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index d9dd138ca9c6..5613cd45866b 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -433,10 +433,14 @@ void rnbd_clt_remove_dev_symlink(struct rnbd_clt_dev *dev)
 	 * i.e. rnbd_clt_unmap_dev_store() leading to a sysfs warning because
 	 * of sysfs link already was removed already.
 	 */
-	if (dev->blk_symlink_name && try_module_get(THIS_MODULE)) {
-		sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
+	if (dev->blk_symlink_name) {
+		if (try_module_get(THIS_MODULE)) {
+			sysfs_remove_link(rnbd_devs_kobj, dev->blk_symlink_name);
+			module_put(THIS_MODULE);
+		}
+		/* It should be freed always. */
 		kfree(dev->blk_symlink_name);
-		module_put(THIS_MODULE);
+		dev->blk_symlink_name = NULL;
 	}
 }