memory leak in ext4_multi_mount

memory leak in ext4_multi_mount_protect
Status: upstream: reported syz repro on 2020/12/24 09:55
Reported-by: syzbot+d9e482e303930fa4f6ff@syzkaller.appspotmail.com
First crash: 35d, last: 2d03h

Sample crash report:

BUG: memory leak
unreferenced object 0xffff88812577e820 (size 32):
  comm "syz-executor.7", pid 11962, jiffies 4294987164 (age 17.750s)
  hex dump (first 32 bytes):
    68 5d b0 14 81 88 ff ff 00 68 66 25 81 88 ff ff  h].......hf%....
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000005540bc5e>] kmalloc include/linux/slab.h:552 [inline]
    [<000000005540bc5e>] ext4_multi_mount_protect+0x4a6/0x5d0 fs/ext4/mmp.c:367
    [<00000000b2d9ee02>] ext4_fill_super+0x5650/0x5ad0 fs/ext4/super.c:4768
    [<00000000795a5705>] mount_bdev+0x223/0x260 fs/super.c:1366
    [<00000000f2050ca0>] legacy_get_tree+0x2b/0x90 fs/fs_context.c:592
    [<00000000340612ba>] vfs_get_tree+0x28/0x100 fs/super.c:1496
    [<000000002658395a>] do_new_mount fs/namespace.c:2881 [inline]
    [<000000002658395a>] path_mount+0xc5e/0x1170 fs/namespace.c:3211
    [<00000000f804b13d>] do_mount fs/namespace.c:3224 [inline]
    [<00000000f804b13d>] __do_sys_mount fs/namespace.c:3432 [inline]
    [<00000000f804b13d>] __se_sys_mount fs/namespace.c:3409 [inline]
    [<00000000f804b13d>] __x64_sys_mount+0x18e/0x1d0 fs/namespace.c:3409
    [<00000000a41d28f9>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<00000000dc99c7c9>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Crashes (6):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	Maintainers
ci-upstream-gce-leak	2021/01/23 05:19	upstream	83d09ad4	4080af96	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci-upstream-gce-leak	2021/01/21 18:14	upstream	9791581c	d4f4eca5	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci-upstream-gce-leak	2021/01/16 15:36	upstream	1d94330a	65a7a854	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci-upstream-gce-leak	2021/01/14 23:51	upstream	65f0d241	65a7a854	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci-upstream-gce-leak	2021/01/04 06:06	upstream	e71ba945	79264ae3	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci-upstream-gce-leak	2020/12/20 09:53	upstream	467f8165	04201c06	.config	log	report	syz	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu