From: bot+bpf-ci@kernel.org
To: jolsa@kernel.org,rostedt@kernel.org,revest@google.com,mark.rutland@arm.com
Cc: bpf@vger.kernel.org,linux-kernel@vger.kernel.org,linux-trace-kernel@vger.kernel.org,linux-arm-kernel@lists.infradead.org,ast@kernel.org,daniel@iogearbox.net,andrii@kernel.org,menglong8.dong@gmail.com,song@kernel.org,ast@kernel.org,andrii@kernel.org,daniel@iogearbox.net,martin.lau@kernel.org,eddyz87@gmail.com,yonghong.song@linux.dev,clm@meta.com,ihor.solodrai@linux.dev
Subject: Re: [PATCHv3 bpf-next 5/8] ftrace: Add update_ftrace_direct_mod function
Date: Thu, 20 Nov 2025 22:23:47 +0000 (UTC) [thread overview]
Message-ID: <a302c70bc1914835ea69c8b30105741b1d1d06d549ef95b9650d0827e0ca276a@mail.kernel.org> (raw)
In-Reply-To: <20251120212402.466524-6-jolsa@kernel.org>
[-- Attachment #1: Type: text/plain, Size: 1662 bytes --]
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index c571deeff..4e2c0ed76 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
[ ... ]
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index cc730a8fd..5243aefb6 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
[ ... ]
> @@ -6486,6 +6486,74 @@ int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash)
> return err;
> }
>
> +int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, bool do_direct_lock)
> +{
> + struct ftrace_hash *orig_hash = ops->func_hash->filter_hash;
^^^^^^^^^^^^^^^^
Can this crash if ops->func_hash is NULL? In update_ftrace_direct_add()
and update_ftrace_direct_del(), there's a defensive check:
old_filter_hash = ops->func_hash ? ops->func_hash->filter_hash : NULL;
But update_ftrace_direct_mod() dereferences ops->func_hash before any
validation checks occur. The check_direct_multi(ops) validation happens
later, but the dereference occurs first at function entry.
> + struct ftrace_func_entry *entry, *tmp;
> + static struct ftrace_ops tmp_ops = {
> + .func = ftrace_stub,
> + .flags = FTRACE_OPS_FL_STUB,
> + };
> + unsigned long size, i;
> + int err;
> +
> + if (!hash_count(hash))
> + return -EINVAL;
> + if (check_direct_multi(ops))
> + return -EINVAL;
[ ... ]
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/19552032346
next prev parent reply other threads:[~2025-11-20 22:23 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-20 21:23 [PATCHv3 bpf-next 0/8] ftrace,bpf: Use single direct ops for bpf trampolines Jiri Olsa
2025-11-20 21:23 ` [PATCHv3 bpf-next 1/8] ftrace: Make alloc_and_copy_ftrace_hash direct friendly Jiri Olsa
2025-11-20 21:23 ` [PATCHv3 bpf-next 2/8] ftrace: Export some of hash related functions Jiri Olsa
2025-11-20 21:23 ` [PATCHv3 bpf-next 3/8] ftrace: Add update_ftrace_direct_add function Jiri Olsa
2025-11-20 21:23 ` [PATCHv3 bpf-next 4/8] ftrace: Add update_ftrace_direct_del function Jiri Olsa
2025-11-20 22:23 ` bot+bpf-ci
2025-11-21 13:52 ` Jiri Olsa
2025-11-20 21:23 ` [PATCHv3 bpf-next 5/8] ftrace: Add update_ftrace_direct_mod function Jiri Olsa
2025-11-20 22:23 ` bot+bpf-ci [this message]
2025-11-21 13:53 ` Jiri Olsa
2025-11-20 21:24 ` [PATCHv3 bpf-next 6/8] bpf: Add trampoline ip hash table Jiri Olsa
2025-11-20 21:24 ` [PATCHv3 bpf-next 7/8] ftrace: Factor ftrace_ops ops_func interface Jiri Olsa
2025-11-20 21:24 ` [PATCHv3 bpf-next 8/8] bpf, x86: Use single ftrace_ops for direct calls Jiri Olsa
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