memory leak in ext4_multi_mount

memory leak in ext4_multi_mount_protect
Status: upstream: reported C repro on 2020/12/24 09:55
Reported-by: syzbot+d9e482e303930fa4f6ff@syzkaller.appspotmail.com
Fix commit: 618f003199c6 ext4: fix memory leak in ext4_fill_super
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386 ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-arm32]
First crash: 216d, last: 34d

Patch testing requests:
Created	Duration	User	Patch	Repo	Result
2021/04/30 18:23	17m	paskripkin@gmail.com		https://linux.googlesource.com/linux/kernel/git/torvalds/linux refs/changes/76/10176/6	OK
2021/04/12 19:57	17m	paskripkin@gmail.com		https://linux.googlesource.com/linux/kernel/git/torvalds/linux refs/changes/76/10176/1	OK

Sample crash report:

executing program
BUG: memory leak
unreferenced object 0xffff888111edd780 (size 32):
  comm "syz-executor633", pid 8448, jiffies 4294951405 (age 17.620s)
  hex dump (first 32 bytes):
    10 64 d1 0f 81 88 ff ff 00 10 7e 12 81 88 ff ff  .d........~.....
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff81744606>] kmalloc include/linux/slab.h:554 [inline]
    [<ffffffff81744606>] ext4_multi_mount_protect+0x4a6/0x5d0 fs/ext4/mmp.c:367
    [<ffffffff81783614>] ext4_fill_super+0x56a4/0x5b20 fs/ext4/super.c:4769
    [<ffffffff8154ebf3>] mount_bdev+0x223/0x260 fs/super.c:1367
    [<ffffffff815aee7b>] legacy_get_tree+0x2b/0x90 fs/fs_context.c:592
    [<ffffffff8154c7e8>] vfs_get_tree+0x28/0x100 fs/super.c:1497
    [<ffffffff8158c8ee>] do_new_mount fs/namespace.c:2903 [inline]
    [<ffffffff8158c8ee>] path_mount+0xc3e/0x1120 fs/namespace.c:3233
    [<ffffffff8158d51e>] do_mount fs/namespace.c:3246 [inline]
    [<ffffffff8158d51e>] __do_sys_mount fs/namespace.c:3454 [inline]
    [<ffffffff8158d51e>] __se_sys_mount fs/namespace.c:3431 [inline]
    [<ffffffff8158d51e>] __x64_sys_mount+0x18e/0x1d0 fs/namespace.c:3431
    [<ffffffff842ded2d>] do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
    [<ffffffff84400068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Crashes (12):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Title
ci-upstream-gce-leak	2021/04/09 05:42	upstream	4fa56ad0d12e	6a81331a	.config	log	report	syz	C	memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/06/19 16:09	upstream	b1edae0d5f2e	aba2b2fb	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/06/15 02:37	upstream	009c9aa5be65	1ba81399	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/02/05 06:50	upstream	5c279c4cf206	23a562df	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/02/03 14:52	upstream	3aaf0a27ffc2	624dad51	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/02/01 01:24	upstream	6642d600b541	fc9fd31e	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/01/23 05:19	upstream	83d09ad4b950	4080af96	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/01/21 18:14	upstream	9791581c049c	d4f4eca5	.config	log	report	syz		memory leak in ext4_multi_mount_protect
ci-upstream-gce-leak	2021/01/16 15:36	upstream	1d94330a437a	65a7a854	.config	log	report	syz
ci-upstream-gce-leak	2021/01/14 23:51	upstream	65f0d2414b70	65a7a854	.config	log	report	syz
ci-upstream-gce-leak	2021/01/04 06:06	upstream	e71ba9452f0b	79264ae3	.config	log	report	syz
ci-upstream-gce-leak	2020/12/20 09:53	upstream	467f8165a2b0	04201c06	.config	log	report	syz