[syzbot] memory leak in prctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 77856d911a8c Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f28cbb880000
kernel config: https://syzkaller.appspot.com/x/.config?x=6b1ea4fdbd78230a
dashboard link: https://syzkaller.appspot.com/bug?extid=91edf9178386a07d06a7
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=153ff26f880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1073a993880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/93698bc86a1d/disk-77856d91.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6190640893ad/vmlinux-77856d91.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ddf790b00ced/bzImage-77856d91.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+91edf9...@syzkaller.appspotmail.com

Warning: Permanently added '10.128.0.165' (ECDSA) to the list of known hosts.
executing program
BUG: memory leak
unreferenced object 0xffff88810c4c57a0 (size 32):
comm "syz-executor948", pid 5064, jiffies 4294946184 (age 7.250s)
hex dump (first 32 bytes):
01 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:
[<ffffffff814f8d16>] __do_kmalloc_node mm/slab_common.c:967 [inline]
[<ffffffff814f8d16>] __kmalloc+0x46/0x120 mm/slab_common.c:981
[<ffffffff81564fb7>] kmalloc include/linux/slab.h:584 [inline]
[<ffffffff81564fb7>] anon_vma_name_alloc+0x27/0x60 mm/madvise.c:78
[<ffffffff8128d4df>] prctl_set_vma kernel/sys.c:2324 [inline]
[<ffffffff8128d4df>] __do_sys_prctl+0xaff/0xba0 kernel/sys.c:2627
[<ffffffff848a05d5>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff848a05d5>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84a00087>] entry_SYSCALL_64_after_hwframe+0x63/0xcd



---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches