Subject: [syzbot] [net?] BUG: unable to handle kernel paging request in nsim_bpf

From: syzbot <[email-masked]>
Date: Wed, 08 Nov 2023 21:10:27 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    8de1e7afcc1c Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=158c647b680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3e6feaeda5dcbc27
dashboard link: https://syzkaller.appspot.com/bug?extid=44c2416196b7c607f226
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=104da6eb680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14df3787680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0f00907f9764/disk-8de1e7af.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0502fe78c60d/vmlinux-8de1e7af.xz
kernel image: https://storage.googleapis.com/syzbot-assets/192135168cc0/Image-8de1e7af.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 6085 Comm: syz-executor153 Not tainted 6.6.0-rc7-syzkaller-g8de1e7afcc1c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : nsim_setup_prog_hw_checks drivers/net/netdevsim/bpf.c:320 [inline]
pc : nsim_bpf+0x1e0/0xae0 drivers/net/netdevsim/bpf.c:562
lr : nsim_bpf+0x8c/0xae0 drivers/net/netdevsim/bpf.c:554
sp : ffff800096c67790
x29: ffff800096c677a0 x28: dfff800000000000 x27: ffff700012d8cf00
x26: dfff800000000000 x25: ffff800096c67a00 x24: 0000000000000008
x23: ffff800096c67820 x22: 0000000000000018 x21: ffff800096c67820
x20: ffff0000d3834cc0 x19: ffff0000d3834000 x18: ffff800096c67580
x17: ffff8000805c1258 x16: ffff80008030c738 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000003
x11: ffff0000d4ab3780 x10: 00000000000000bc x9 : ffff800085ce8bf0
x8 : 0000000000000003 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800092dee000 x4 : 0000000000000000 x3 : ffff80008030c754
x2 : 0000000000000000 x1 : ffff80009001ef50 x0 : 0000000000000001
Call trace:
 nsim_setup_prog_hw_checks drivers/net/netdevsim/bpf.c:320 [inline]
 nsim_bpf+0x1e0/0xae0 drivers/net/netdevsim/bpf.c:562
 dev_xdp_install+0x124/0x2f0 net/core/dev.c:9199
 dev_xdp_attach+0xa4c/0xcc8 net/core/dev.c:9351
 dev_xdp_attach_link net/core/dev.c:9370 [inline]
 bpf_xdp_link_attach+0x300/0x710 net/core/dev.c:9540
 link_create+0x2c0/0x68c kernel/bpf/syscall.c:4954
 __sys_bpf+0x4d4/0x5dc kernel/bpf/syscall.c:5414
 __do_sys_bpf kernel/bpf/syscall.c:5448 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5446 [inline]
 __arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:5446
 __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
 el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
Code: 96b3720d f94002c8 91006116 d343fec8 (387a6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	96b3720d 	bl	0xfffffffffacdc834
   4:	f94002c8 	ldr	x8, [x22]
   8:	91006116 	add	x22, x8, #0x18
   c:	d343fec8 	lsr	x8, x22, #3
* 10:	387a6908 	ldrb	w8, [x8, x26] <-- trapping instruction

---
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