Hi,

I've got the following error report while fuzzing the kernel with syzkaller.

On commit 2868b2513aa732a99ea4a0a6bf10dc93c1f3dac2 (4.11+).

A reproducer and .config are attached.

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 0 PID: 5226 Comm: a.out Not tainted 4.11.0+ #331
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006b958000 task.stack: ffff880064328000
RIP: 0010:__free_pages+0x0/0x20 ./include/linux/list.h:92
RSP: 0018:ffff88006432f980 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff880066c44358 RCX: 1ffff1000cd88843
RDX: dead4ead00000000 RSI: 0000000000000001 RDI: dead4ead00000000
RBP: ffff88006432f9d8 R08: 1ffff1000c865eca R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000020 R14: ffff880066c44200 R15: dffffc0000000000
FS:  00007fc454ac67c0(0000) GS:ffff88006ca00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020002000 CR3: 000000006affa000 CR4: 00000000000006f0
Call Trace:
 sg_finish_rem_req+0x2a6/0x320 drivers/scsi/sg.c:1839
 sg_new_read+0x3c/0x430 drivers/scsi/sg.c:567
 sg_read+0x866/0x1830 drivers/scsi/sg.c:455
 __vfs_read+0x5c3/0x750 fs/read_write.c:450
 vfs_read+0x11e/0x350 fs/read_write.c:473
 SYSC_read fs/read_write.c:589
 SyS_read+0xfb/0x230 fs/read_write.c:582
 entry_SYSCALL_64_fastpath+0x1f/0xbe arch/x86/entry/entry_64.S:204
RIP: 0033:0x7fc4541d9b79
RSP: 002b:00007ffc570f28e8 EFLAGS: 00000297 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ffc570f2bc0 RCX: 00007fc4541d9b79
RDX: 0000000000000000 RSI: 0000000020002f36 RDI: 0000000000000003
RBP: 00000000004010d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000
R13: 00007ffc570f2bc0 R14: 0000000000000000 R15: 0000000000000000
Code: 60 fc ff ff e8 02 35 14 00 4c 8b 95 48 fc ff ff 4c 8b 9d 50 fc
ff ff 4c 8b 8d 58 fc ff ff 48 8b 8d 60 fc ff ff e9 73 f9 ff ff 90 <f0>
ff 4f 1c 75 16 55 85 f6 48 89 e5 74 07 e8 5d 2f ff ff 5d c3
RIP: __free_pages+0x0/0x20 RSP: ffff88006432f980