[syzbot] general protection fault in udmabuf_create

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7999516e20bd Add linux-next specific files for 20210806
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10f15f8e300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2f518e910b029c31
dashboard link: https://syzkaller.appspot.com/bug?extid=e9cd3122a37c5d6c51e8
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1181099a300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11b6fce9300000

The issue was bisected to:

commit 16c243e99d335e1ef3059871897119affc98b493
Author: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Date:   Wed Jun 9 18:29:15 2021 +0000

    udmabuf: Add support for mapping hugepages (v4)

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12f73dc9300000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11f73dc9300000
console output: https://syzkaller.appspot.com/x/log.txt?x=16f73dc9300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e9cd3122a37c5d6c51e8@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")

general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 6603 Comm: syz-executor127 Not tainted 5.14.0-rc4-next-20210806-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:_compound_head include/linux/page-flags.h:187 [inline]
RIP: 0010:get_page include/linux/mm.h:1203 [inline]
RIP: 0010:udmabuf_create+0x664/0x16f0 drivers/dma-buf/udmabuf.c:236
Code: 03 48 89 84 24 90 00 00 00 e9 38 01 00 00 e8 23 7a f7 fc 4d 89 f4 49 c1 e4 06 4c 03 24 24 49 8d 7c 24 08 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 d3 0d 00 00 4d 8b 6c 24 08 31 ff 4c 89 eb 83
RSP: 0018:ffffc90002d7fc70 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888023f69c80 RSI: ffffffff847e4f3d RDI: 0000000000000008
RBP: 0000000000000000 R08: fffffffffffff000 R09: 0000000000000000
R10: ffffffff847e50f5 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000935300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000020c CR3: 0000000018d16000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 udmabuf_ioctl_create drivers/dma-buf/udmabuf.c:305 [inline]
 udmabuf_ioctl+0x152/0x2c0 drivers/dma-buf/udmabuf.c:336
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43eed9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff10c6b558 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043eed9
RDX: 0000000020000180 RSI: 0000000040187542 RDI: 0000000000000003
RBP: 0000000000402ec0 R08: 0000000000400488 R09: 0000000000400488
R10: 0000000000400488 R11: 0000000000000246 R12: 0000000000402f50
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488
Modules linked in:
---[ end trace e38355abd6102561 ]---
RIP: 0010:_compound_head include/linux/page-flags.h:187 [inline]
RIP: 0010:get_page include/linux/mm.h:1203 [inline]
RIP: 0010:udmabuf_create+0x664/0x16f0 drivers/dma-buf/udmabuf.c:236
Code: 03 48 89 84 24 90 00 00 00 e9 38 01 00 00 e8 23 7a f7 fc 4d 89 f4 49 c1 e4 06 4c 03 24 24 49 8d 7c 24 08 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 d3 0d 00 00 4d 8b 6c 24 08 31 ff 4c 89 eb 83
RSP: 0018:ffffc90002d7fc70 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888023f69c80 RSI: ffffffff847e4f3d RDI: 0000000000000008
RBP: 0000000000000000 R08: fffffffffffff000 R09: 0000000000000000
R10: ffffffff847e50f5 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000935300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff86ca0778 CR3: 0000000018d16000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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