From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E04B423D7CE for ; Thu, 27 Nov 2025 03:52:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764215572; cv=none; b=mSbyUqVhFNrcSSJr1lKagOrhJ1JRW5659s7pnj1Z8JMsZ8fICRgj4Qfgnn2cFCdOTsievggY75gDTLPFW3dUBPlgGoawWzzzsICtshH9DzcIV8AfED1tRMLzMqE2NZk2waT0kfgyV3XYP6XzxvWl2cWR1nBA3j7Iuesu0TNX8Cw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764215572; c=relaxed/simple; bh=eW193bAsfSUP6/8bJAgVDagf6DIBrjQtuSLrlabzKcs=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=C3TTk3o0jOqGSKGlXniHn9KQc99bSQJFldoEvubDF02bFxj5bb1HQSPa5RIcPyGhUshsSuMOiBXGre+qJILG25y0HIseLsxB/MkGdJBoORzOSG1UfzaLkTE3xCLO/piTsrhhxRLAEr3GCZ3nm0UFJ6zJpSeOrn/sR/trddZITCU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nnovECHs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nnovECHs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7748EC4CEF8; Thu, 27 Nov 2025 03:52:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764215571; bh=eW193bAsfSUP6/8bJAgVDagf6DIBrjQtuSLrlabzKcs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nnovECHsUqkppVaOExujL1jEnffuj4M3gc4BYlvC+KavKWWwIHrNWPuqAjOBxyZGz 0UBIun3MZRzkeRKpJnmrEdtguZrAB4VA1WGJRMYwQbLO7E+AY6ky/XBc/YvdBlhcrv sz952hZQ5imoK/gYyGl92vOo84Qs66aUwMew1REwUiecQdZk0g3OGgVKGnmZ48D1GG 4xaeHnalFMhR0NwV3FpZoKvNVj2N3yFvIyJVy/2APVVkNJNpyoWYoEPbpgZu0qdBx0 1IhuXkyR+fzxbYEb2fWEPk+Txt54Cb12o2JFs70DydWtIOgerc5cOm/wuPc57T6XxZ f/pvqTNOOCtow== Date: Thu, 27 Nov 2025 12:52:48 +0900 From: Masami Hiramatsu (Google) To: Ye Bin Cc: naveen@kernel.org, davem@davemloft.net, linux-trace-kernel@vger.kernel.org, yebin10@huawei.com Subject: Re: [PATCH] kprobes: avoid crash when rmmod/insmod modules after ftrace_disabled Message-Id: <20251127125248.a1367d15c0bbc7faad3b0e87@kernel.org> In-Reply-To: <20251125020536.2484381-1-yebin@huaweicloud.com> References: <20251125020536.2484381-1-yebin@huaweicloud.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Hi, Thanks for reporting! On Tue, 25 Nov 2025 10:05:36 +0800 Ye Bin wrote: > From: Ye Bin > > There's a issue as follows when rmmod modules after ftrace disabled: You may see something like; Failed to unregister kprobe-ftrace (error -19) or Failed to disarm kprobe-ftrace at (error -19) right before this BUG, don't you? If you reported with that line, it's more easier to understand. > BUG: unable to handle page fault for address: fffffbfff805000d > PGD 817fcc067 P4D 817fcc067 PUD 817fc8067 PMD 101555067 PTE 0 > Oops: Oops: 0000 [#1] SMP KASAN PTI > CPU: 4 UID: 0 PID: 2012 Comm: rmmod Tainted: G W OE > Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE > RIP: 0010:kprobes_module_callback+0x89/0x790 > RSP: 0018:ffff88812e157d30 EFLAGS: 00010a02 > RAX: 1ffffffff805000d RBX: dffffc0000000000 RCX: ffffffff86a8de90 > RDX: ffffed1025c2af9b RSI: 0000000000000008 RDI: ffffffffc0280068 > RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed1025c2af9a > R10: ffff88812e157cd7 R11: 205d323130325420 R12: 0000000000000002 > R13: ffffffffc0290488 R14: 0000000000000002 R15: ffffffffc0280040 > FS: 00007fbc450dd740(0000) GS:ffff888420331000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: fffffbfff805000d CR3: 000000010f624000 CR4: 00000000000006f0 > Call Trace: > > notifier_call_chain+0xc6/0x280 > blocking_notifier_call_chain+0x60/0x90 > __do_sys_delete_module.constprop.0+0x32a/0x4e0 > do_syscall_64+0x5d/0xfa0 > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > The above issue occurs because the kprobe was not removed from the hash > list after ftrace_disable. > To prevent the system from restarting unexpectedly after ftrace_disable, > in such cases, unregister_kprobe() ensures that the probe is removed from > the hash list, preventing subsequent access to already freed memory. > > Fixes: 6f0f1dd71953 ("kprobes: Cleanup disabling and unregistering path") > Signed-off-by: Ye Bin > --- > kernel/kprobes.c | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index ab8f9fc1f0d1..d735a608b810 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1731,8 +1731,30 @@ static int __unregister_kprobe_top(struct kprobe *p) > > /* Disable kprobe. This will disarm it if needed. */ > ap = __disable_kprobe(p); > - if (IS_ERR(ap)) > - return PTR_ERR(ap); > + if (IS_ERR(ap)) { > + int ret = PTR_ERR(ap); > + > + /* > + * If ftrace disabled we need to delete kprobe node from > + * hlist or aggregation list. If nodes are not removed when > + * modules are removed, the already released nodes will > + * remain in the linked list. Subsequent access to the > + * linked list may then trigger exceptions. > + */ > + if (ret != -ENODEV) > + return ret; > + > + ap = __get_valid_kprobe(p); > + if (!ap) > + return ret; > + > + if (ap == p) > + hlist_del_rcu(&ap->hlist); > + else > + list_del_rcu(&p->list); Instead of repeating this process, we should ignore -ENODEV error from ftrace directly. BTW, ftrace_disabled is set when ftrace_kill() is called, that means ftrace is no more usable. So I think we can just ignore ftrace operation in __disarm_kprobe_ftrace(). Thank you, > + > + return ret; > + } > > WARN_ON(ap != p && !kprobe_aggrprobe(ap)); > > -- > 2.34.1 > -- Masami Hiramatsu (Google)