[v5.15] Internal error in copy_from_kernel_nofault

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1480b2f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=87280fbdce4b4b86260d
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+87280f...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4669 Comm: syz.2.158 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 22400405 (nzCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : copy_from_kernel_nofault+0x9c/0x330 mm/maccess.c:37
lr : copy_from_kernel_nofault+0x78/0x330 mm/maccess.c:37
sp : ffff80001bb97640
x29: ffff80001bb97640 x28: 0000000000000000 x27: dfff800000000000
x26: 1fffe0001a90e979 x25: 00000000fffffff2 x24: ffff80001bb97720
x23: 0000000000000000 x22: 0000000000000008 x21: f89d80000a770438
x20: ffff80001bb97728 x19: ffff0000d4874bc8 x18: 0000000000000001
x17: 0000000000000002 x16: ffff800008683dec x15: 0000000000000036
x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000ff0100
x11: 0000000000000001 x10: 0000000000000002 x9 : ffff0000d4873680
x8 : 1ffff00003772ee4 x7 : 0000000000000000 x6 : 0000000058587025
x5 : ffff80001bb97745 x4 : ffff800013919d84 x3 : ffff800008587df4
x2 : 0000000000000010 x1 : 0000000000000010 x0 : 0000000000000007
Call trace:
copy_from_kernel_nofault+0x9c/0x330 mm/maccess.c:37
bpf_bprintf_prepare+0xc60/0x119c kernel/bpf/helpers.c:885
____bpf_snprintf kernel/bpf/helpers.c:1011 [inline]
bpf_snprintf+0xcc/0x14c kernel/bpf/helpers.c:995
bpf_prog_73d831df50e9c6a4+0x78/0x6fc
bpf_dispatcher_xdp_func+0x30/0x44 net/core/filter.c:10943
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run_xdp include/linux/filter.h:810 [inline]
bpf_test_run+0x2bc/0x820 net/bpf/test_run.c:117
bpf_prog_test_run_xdp+0x31c/0x7bc net/bpf/test_run.c:812
bpf_prog_test_run+0x2e0/0x374 kernel/bpf/syscall.c:3368
__sys_bpf+0x4ac/0x5f0 kernel/bpf/syscall.c:4669
__do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
__arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:4753
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: aa0803f6 d343ff08 2a1703f9 f94002bc (387b6908)
---[ end trace bd88d65619f9e266 ]---
----------------
Code disassembly (best guess):
0: aa0803f6 mov x22, x8
4: d343ff08 lsr x8, x24, #3
8: 2a1703f9 mov w25, w23
c: f94002bc ldr x28, [x21]
* 10: 387b6908 ldrb w8, [x8, x27] <-- trapping instruction


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=13c905a2580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=87280fbdce4b4b86260d
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13e269a2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17c905a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+87280f...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:

CPU: 0 PID: 4219 Comm: syz.0.17 Not tainted 5.15.189-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025

pstate: 62400405 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : copy_from_kernel_nofault+0x134/0x330 mm/maccess.c:39
lr : copy_from_kernel_nofault+0x10c/0x330 mm/maccess.c:39
sp : ffff80001fe17760
x29: ffff80001fe17760 x28: 0000000000000004 x27: dfff800000000000
x26: 1fffe00019c0c611 x25: 00000000fffffff2 x24: ffff80001fe17840
x23: 0000000000000000 x22: 0000000000000000 x21: ffffffff860bffff
x20: ffff80001fe17844 x19: ffff0000ce063088 x18: 0000000000000002
x17: 0000000000000000 x16: ffff800008683e84 x15: 0000000000000036

x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000ff0100

x11: 0000000000000002 x10: 0000000000000000 x9 : 1ffff00003fc2f08
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000058587025
x5 : ffff80001fe17865 x4 : ffff800013919d84 x3 : ffff800008587df4
x2 : 0000000000000004 x1 : 0000000000000004 x0 : 0000000000000003
Call trace:
copy_from_kernel_nofault+0x134/0x330 mm/maccess.c:39

bpf_bprintf_prepare+0xc60/0x119c kernel/bpf/helpers.c:885
____bpf_snprintf kernel/bpf/helpers.c:1011 [inline]
bpf_snprintf+0xcc/0x14c kernel/bpf/helpers.c:995

bpf_prog_f2f741945f01d4c6+0x78/0x808
bpf_dispatcher_nop_func include/linux/bpf.h:790 [inline]
__bpf_prog_run include/linux/filter.h:628 [inline]
bpf_prog_run include/linux/filter.h:635 [inline]
bpf_prog_run_pin_on_cpu include/linux/filter.h:652 [inline]
bpf_flow_dissect+0x100/0x408 net/core/flow_dissector.c:896
bpf_prog_test_run_flow_dissector+0x330/0x4c4 net/bpf/test_run.c:907

bpf_prog_test_run+0x2e0/0x374 kernel/bpf/syscall.c:3368
__sys_bpf+0x4ac/0x5f0 kernel/bpf/syscall.c:4669
__do_sys_bpf kernel/bpf/syscall.c:4755 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4753 [inline]
__arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:4753
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Code: d343ff09 2a1703f9 12000b0a b94002a8 (11000d4a)
---[ end trace bbe2110391fedf53 ]---

----------------
Code disassembly (best guess):

0: d343ff09 lsr x9, x24, #3
4: 2a1703f9 mov w25, w23
8: 12000b0a and w10, w24, #0x7
c: b94002a8 ldr w8, [x21]
* 10: 11000d4a add w10, w10, #0x3 <-- trapping instruction


---
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