WARNING: kmalloc bug in map_get_next_key

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    c5c7d7f3c451 Merge branch 'bpf-sock-hashmap'
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13ec7877800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=10c4dc62055b68f5
dashboard link: https://syzkaller.appspot.com/bug?extid=e4566d29080e7f3460ff
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12c35417800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=178c97f7800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e4566d29080e7f3460ff@xxxxxxxxxxxxxxxxxxxxxxxxx

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
WARNING: CPU: 0 PID: 4499 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70  
mm/slab_common.c:996
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 4499 Comm: syz-executor050 Not tainted 4.17.0-rc3+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:996
RSP: 0018:ffff8801d907fc58 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801aeecb280 RCX: ffffffff8185ebd7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000ffffffe1
RBP: ffff8801d907fc58 R08: ffff8801adb5e1c0 R09: ffffed0035a84700
R10: ffffed0035a84700 R11: ffff8801ad423803 R12: ffff8801aeecb280
R13: 00000000fffffff4 R14: ffff8801ad891a00 R15: 00000000014200c0
 __do_kmalloc mm/slab.c:3713 [inline]
 __kmalloc+0x25/0x760 mm/slab.c:3727
 kmalloc include/linux/slab.h:517 [inline]
 map_get_next_key+0x24a/0x640 kernel/bpf/syscall.c:858
 __do_sys_bpf kernel/bpf/syscall.c:2131 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:2096 [inline]
 __x64_sys_bpf+0x354/0x4f0 kernel/bpf/syscall.c:2096
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fd89
RSP: 002b:00007ffd6aab4668 EFLAGS: 00000213 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fd89
RDX: 0000000000000007 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 00000000004016b0
R13: 0000000000401740 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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