general protection fault in xsk_is_setup_for_bpf_map

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dc1a9bf2 octeontx2-pf: Add UDP segmentation offload support
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1442d38e900000
kernel config: https://syzkaller.appspot.com/x/.config?x=b6856d16f78d8fa9
dashboard link: https://syzkaller.appspot.com/bug?extid=febe51d44243fbc564ee
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1019da25900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15988279900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+febe51...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000020: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000100-0x0000000000000107]
CPU: 1 PID: 8180 Comm: syz-executor241 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:xsk_is_setup_for_bpf_map+0xbd/0x140 net/xdp/xsk.c:39
Code: 80 3c 02 00 0f 85 8b 00 00 00 4c 8b a3 e8 04 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 00 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 6f 49 83 bc 24 00 01 00 00 00 74 12 41 bc 01 00 00
RSP: 0018:ffffc90005787c30 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88808880f000 RCX: ffffffff87effd24
RDX: 0000000000000020 RSI: ffffffff87efc58b RDI: 0000000000000100
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff888094f6ea00
R10: 000000000000002c R11: 0000000000000000 R12: 0000000000000000
R13: ffff888082808a80 R14: ffff88808880f000 R15: 000000000000002c
FS: 0000000000767940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000077fffb CR3: 00000000a939a000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
xsk_map_update_elem+0x1bc/0x9d0 net/xdp/xskmap.c:188
bpf_map_update_value.isra.0+0x715/0x900 kernel/bpf/syscall.c:200
map_update_elem kernel/bpf/syscall.c:1120 [inline]
__do_sys_bpf+0x320b/0x4b30 kernel/bpf/syscall.c:4186
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x44c4f9
Code: e8 1c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 04 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc6d766ac8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000044c4f9
RDX: 000000000000002c RSI: 0000000020003000 RDI: 0000000000000002
RBP: 0000000000000000 R08: fffffffffffffff5 R09: fffffffffffffff5
R10: fffffffffffffff5 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 6b3dd16ce201e2fa ]---
RIP: 0010:xsk_is_setup_for_bpf_map+0xbd/0x140 net/xdp/xsk.c:39
Code: 80 3c 02 00 0f 85 8b 00 00 00 4c 8b a3 e8 04 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 00 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 6f 49 83 bc 24 00 01 00 00 00 74 12 41 bc 01 00 00
RSP: 0018:ffffc90005787c30 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88808880f000 RCX: ffffffff87effd24
RDX: 0000000000000020 RSI: ffffffff87efc58b RDI: 0000000000000100
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff888094f6ea00
R10: 000000000000002c R11: 0000000000000000 R12: 0000000000000000
R13: ffff888082808a80 R14: ffff88808880f000 R15: 000000000000002c
FS: 0000000000767940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000077fffb CR3: 00000000a939a000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[Hillf Danton]

Wed, 02 Sep 2020 00:27:22 -0700

Fix 7361f9c3d719 ("xsk: Move fill and completion rings to buffer pool")
by adding check to see if pool is valid.

--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -36,7 +36,7 @@ static DEFINE_PER_CPU(struct list_head,
bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
{
return READ_ONCE(xs->rx) && READ_ONCE(xs->umem) &&
- (xs->pool->fq || READ_ONCE(xs->fq_tmp));
+ ((xs->pool && xs->pool->fq) || READ_ONCE(xs->fq_tmp));
}

void xsk_set_rx_need_wakeup(struct xsk_buff_pool *pool)