* Re: [syzbot] [bpf?] WARNING in do_misc_fixups
2025-08-04 5:08 [syzbot] [bpf?] WARNING in do_misc_fixups syzbot
@ 2025-08-04 16:05 ` Alexei Starovoitov
2025-08-05 13:53 ` Jiri Olsa
1 sibling, 0 replies; 4+ messages in thread
From: Alexei Starovoitov @ 2025-08-04 16:05 UTC (permalink / raw)
To: syzbot
Cc: Andrii Nakryiko, Alexei Starovoitov, bpf, Daniel Borkmann, Eduard,
Hao Luo, John Fastabend, Jiri Olsa, KP Singh, LKML,
Martin KaFai Lau, Stanislav Fomichev, Song Liu, syzkaller-bugs,
Yonghong Song
On Sun, Aug 3, 2025 at 10:08 PM syzbot
<syzbot+a9ed3d9132939852d0df@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: a6923c06a3b2 Merge tag 'bpf-fixes' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1561dcf0580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f89bb9497754f485
> dashboard link: https://syzkaller.appspot.com/bug?extid=a9ed3d9132939852d0df
> compiler: aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165d0aa2580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117bd834580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-a6923c06.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/9862ca8219e0/vmlinux-a6923c06.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/042ebe320cfd/Image-a6923c06.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a9ed3d9132939852d0df@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> verifier bug: not inlined functions bpf_probe_read_kernel_str#115 is missing func(1)
> WARNING: CPU: 1 PID: 3594 at kernel/bpf/verifier.c:22838 do_misc_fixups+0x1784/0x1ab4 kernel/bpf/verifier.c:22838
This is an odd config with BPF_SYSCALL=y and BPF_EVENTS=n.
One approach to mitigate this is to add a check that fn->func is valid
in get_helper_proto().
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [syzbot] [bpf?] WARNING in do_misc_fixups
2025-08-04 5:08 [syzbot] [bpf?] WARNING in do_misc_fixups syzbot
2025-08-04 16:05 ` Alexei Starovoitov
@ 2025-08-05 13:53 ` Jiri Olsa
2025-08-05 14:23 ` syzbot
1 sibling, 1 reply; 4+ messages in thread
From: Jiri Olsa @ 2025-08-05 13:53 UTC (permalink / raw)
To: syzbot
Cc: andrii, ast, bpf, daniel, eddyz87, haoluo, john.fastabend,
kpsingh, linux-kernel, martin.lau, sdf, song, syzkaller-bugs,
yonghong.song
On Sun, Aug 03, 2025 at 10:08:32PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: a6923c06a3b2 Merge tag 'bpf-fixes' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1561dcf0580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=f89bb9497754f485
> dashboard link: https://syzkaller.appspot.com/bug?extid=a9ed3d9132939852d0df
> compiler: aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165d0aa2580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117bd834580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/fa3fbcfdac58/non_bootable_disk-a6923c06.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/9862ca8219e0/vmlinux-a6923c06.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/042ebe320cfd/Image-a6923c06.gz.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a9ed3d9132939852d0df@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> verifier bug: not inlined functions bpf_probe_read_kernel_str#115 is missing func(1)
> WARNING: CPU: 1 PID: 3594 at kernel/bpf/verifier.c:22838 do_misc_fixups+0x1784/0x1ab4 kernel/bpf/verifier.c:22838
> Modules linked in:
> CPU: 1 UID: 0 PID: 3594 Comm: syz.2.17 Not tainted 6.16.0-syzkaller-11105-ga6923c06a3b2 #0 PREEMPT
> Hardware name: linux,dummy-virt (DT)
> pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
> pc : do_misc_fixups+0x1784/0x1ab4 kernel/bpf/verifier.c:22838
> lr : do_misc_fixups+0x1784/0x1ab4 kernel/bpf/verifier.c:22838
> sp : ffff80008936b9a0
> x29: ffff80008936b9a0 x28: f5ff8000832f5000 x27: 000000000000000a
> x26: f8f0000007ba8000 x25: 0000000000000000 x24: f8f0000007bae200
> x23: 000000000000f0ff x22: 000000000000000a x21: f8f0000007bae128
> x20: f8f0000007ba8aa8 x19: ffff80008243e828 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000 x15: ffff800081b73b80
> x14: 0000000000000342 x13: 0000000000000000 x12: 0000000000000002
> x11: 00000000000000c0 x10: 646e0773d90f24cc x9 : 73727a981a23afd7
> x8 : fcf0000007bb36f8 x7 : 0000000000000190 x6 : 0000003978391654
> x5 : 0000000000000001 x4 : fbffff3fffffffff x3 : 000000000000ffff
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : fcf0000007bb2500
> Call trace:
> do_misc_fixups+0x1784/0x1ab4 kernel/bpf/verifier.c:22838 (P)
> bpf_check+0x1308/0x2a8c kernel/bpf/verifier.c:24739
> bpf_prog_load+0x634/0xb74 kernel/bpf/syscall.c:2979
> __sys_bpf+0x2e0/0x1a3c kernel/bpf/syscall.c:6029
> __do_sys_bpf kernel/bpf/syscall.c:6139 [inline]
> __se_sys_bpf kernel/bpf/syscall.c:6137 [inline]
> __arm64_sys_bpf+0x24/0x34 kernel/bpf/syscall.c:6137
> __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
> invoke_syscall+0x48/0x110 arch/arm64/kernel/syscall.c:49
> el0_svc_common.constprop.0+0x40/0xe0 arch/arm64/kernel/syscall.c:132
> do_el0_svc+0x1c/0x28 arch/arm64/kernel/syscall.c:151
> el0_svc+0x34/0x10c arch/arm64/kernel/entry-common.c:879
> el0t_64_sync_handler+0xa0/0xe4 arch/arm64/kernel/entry-common.c:898
> el0t_64_sync+0x1a4/0x1a8 arch/arm64/kernel/entry.S:596
> ---[ end trace 0000000000000000 ]---
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
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>
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>
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trying suggested fix by Alexei
jirka
#syz test
---
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0806295945e4..6aa303f76849 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11344,6 +11344,13 @@ static bool can_elide_value_nullness(enum bpf_map_type type)
}
}
+static bool is_valid_proto(const struct bpf_func_proto *fn, int func_id)
+{
+ if (func_id == BPF_FUNC_tail_call)
+ return true;
+ return fn && fn->func;
+}
+
static int get_helper_proto(struct bpf_verifier_env *env, int func_id,
const struct bpf_func_proto **ptr)
{
@@ -11354,7 +11361,7 @@ static int get_helper_proto(struct bpf_verifier_env *env, int func_id,
return -EINVAL;
*ptr = env->ops->get_func_proto(func_id, env->prog);
- return *ptr ? 0 : -EINVAL;
+ return is_valid_proto(*ptr, func_id) ? 0 : -EINVAL;
}
static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
^ permalink raw reply related [flat|nested] 4+ messages in thread