memory leak in reiserfs_fill_super

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    6794862a Merge tag 'for-5.5-rc1-kconfig-tag' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1158c12ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf3a35184a3ed64
dashboard link: https://syzkaller.appspot.com/bug?extid=1c6756baf4b16b94d2a6
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=165a64fae00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12083661e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1c6756baf4b16b94d2a6@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: memory leak
unreferenced object 0xffff88811ff310c0 (size 32):
  comm "syz-executor671", pid 7128, jiffies 4294943335 (age 13.580s)
  hex dump (first 32 bytes):
    2e 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    01 00 00 00 01 00 00 00 18 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000004089eb3d>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<000000004089eb3d>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<000000004089eb3d>] slab_alloc mm/slab.c:3320 [inline]
    [<000000004089eb3d>] __do_kmalloc mm/slab.c:3654 [inline]
    [<000000004089eb3d>] __kmalloc_track_caller+0x165/0x300 mm/slab.c:3671
    [<000000008421832f>] kstrdup+0x3a/0x70 mm/util.c:60
    [<0000000043bf75e5>] reiserfs_fill_super+0x500/0x1120  
fs/reiserfs/super.c:1946
    [<000000009cbc0e69>] mount_bdev+0x1ce/0x210 fs/super.c:1415
    [<00000000934dd7f3>] get_super_block+0x35/0x40 fs/reiserfs/super.c:2604
    [<00000000cf77f9c8>] legacy_get_tree+0x27/0x80 fs/fs_context.c:647
    [<000000000d70f443>] vfs_get_tree+0x2d/0xe0 fs/super.c:1545
    [<00000000be5ed892>] do_new_mount fs/namespace.c:2822 [inline]
    [<00000000be5ed892>] do_mount+0x97c/0xc80 fs/namespace.c:3142
    [<00000000f546ac03>] ksys_mount+0xab/0x120 fs/namespace.c:3351
    [<000000005818601f>] __do_sys_mount fs/namespace.c:3365 [inline]
    [<000000005818601f>] __se_sys_mount fs/namespace.c:3362 [inline]
    [<000000005818601f>] __x64_sys_mount+0x26/0x30 fs/namespace.c:3362
    [<00000000a358ffb7>] do_syscall_64+0x73/0x220  
arch/x86/entry/common.c:294
    [<00000000cb1c9cc8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

BUG: memory leak
unreferenced object 0xffff8881232e08e0 (size 32):
  comm "syz-executor671", pid 7135, jiffies 4294943878 (age 8.150s)
  hex dump (first 32 bytes):
    2e 00 63 75 72 69 74 79 2e 73 65 6c 69 6e 75 78  ..curity.selinux
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<000000004089eb3d>] kmemleak_alloc_recursive  
include/linux/kmemleak.h:43 [inline]
    [<000000004089eb3d>] slab_post_alloc_hook mm/slab.h:586 [inline]
    [<000000004089eb3d>] slab_alloc mm/slab.c:3320 [inline]
    [<000000004089eb3d>] __do_kmalloc mm/slab.c:3654 [inline]
    [<000000004089eb3d>] __kmalloc_track_caller+0x165/0x300 mm/slab.c:3671
    [<000000008421832f>] kstrdup+0x3a/0x70 mm/util.c:60
    [<0000000043bf75e5>] reiserfs_fill_super+0x500/0x1120  
fs/reiserfs/super.c:1946
    [<000000009cbc0e69>] mount_bdev+0x1ce/0x210 fs/super.c:1415
    [<00000000934dd7f3>] get_super_block+0x35/0x40 fs/reiserfs/super.c:2604
    [<00000000cf77f9c8>] legacy_get_tree+0x27/0x80 fs/fs_context.c:647
    [<000000000d70f443>] vfs_get_tree+0x2d/0xe0 fs/super.c:1545
    [<00000000be5ed892>] do_new_mount fs/namespace.c:2822 [inline]
    [<00000000be5ed892>] do_mount+0x97c/0xc80 fs/namespace.c:3142
    [<00000000f546ac03>] ksys_mount+0xab/0x120 fs/namespace.c:3351
    [<000000005818601f>] __do_sys_mount fs/namespace.c:3365 [inline]
    [<000000005818601f>] __se_sys_mount fs/namespace.c:3362 [inline]
    [<000000005818601f>] __x64_sys_mount+0x26/0x30 fs/namespace.c:3362
    [<00000000a358ffb7>] do_syscall_64+0x73/0x220  
arch/x86/entry/common.c:294
    [<00000000cb1c9cc8>] entry_SYSCALL_64_after_hwframe+0x44/0xa9



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