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 D113138DE3; Fri, 17 Jan 2025 01:23:12 +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=1737076994; cv=none; b=IBr23jgdYbdOdKVGkklSEv2jmhkl5GpS0ziTnS9zKeZFkZFyvi7ocA4YfwptDMNmxoxmC8OZA22ZYOrjTM6fA9M2yFhm4wPvw01aoEEnbarIOdAHB+VzX/OkO5RPVtTWPi8cFdJqp1D2i0Lq7pcDwX/tliYyMBPPifgqSCrFj6M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737076994; c=relaxed/simple; bh=wIT9IZfUMJtxKYEmAWkkr+Vs51mMi8q9ct0lyYCDvHM=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=ivk8qeRtCqCJi9w7tKBUj7FukQgjdFxML/WK/Hwv0ezEXDWFmwDsRTHGNNZHYp4d3vwLcwtoxFGspTrVfRPAdpiqAFEHERPddtRaq2Bm+Z+PFjyHGnrWVFrdL1HOlgZioLdGCNPw6uyH85e8t2VQslBTVhLuxqtJXiU6aQMwa98= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Bqy00K6L; 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="Bqy00K6L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85E20C4CED6; Fri, 17 Jan 2025 01:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737076992; bh=wIT9IZfUMJtxKYEmAWkkr+Vs51mMi8q9ct0lyYCDvHM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Bqy00K6LyPPhuy2uJt4sFf345HeojZCIcneZ6fg38dC+fjoOsdtRXBRckRPRJrdVo JYefeOgjfNFPSw7JRdZRqyCc2Ke5cgCL7htPX2FBawI6usbxUXXeIltvAOSpV7vvqz +m2Lbvhl3IGH/1xGLC6TtSk3wu1c6jj4MlWDpZ+qmIuoy5t/C/r7S67IzKw0LBfC19 xwynJyxWDRlSkzng7lEjHbkk4CtxSH0eplm24itSCbgty7fjhqDueVh1cf6p4BOxzk aZQmTc0/B6NEhE7cA9xp6TuZSPS43QxOdEWej0pER8qn9BYdedGQA9fwyrFD9baaXT lStJC1nfAmZhg== Date: Fri, 17 Jan 2025 10:23:07 +0900 From: Masami Hiramatsu (Google) To: Jiri Olsa Cc: Oleg Nesterov , Masami Hiramatsu , Aleksa Sarai , Eyal Birger , linux-kernel , linux-trace-kernel@vger.kernel.org, BPF-dev-list , Song Liu , Yonghong Song , John Fastabend , peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, x86@kernel.org, linux-api@vger.kernel.org, Andrii Nakryiko , Daniel Borkmann , Alexei Starovoitov , Andrii Nakryiko , "rostedt@goodmis.org" , rafi@rbk.io, Shmulik Ladkani Subject: Re: Crash when attaching uretprobes to processes running in Docker Message-Id: <20250117102307.cf919a0e7e59e3df0ddbcd3c@kernel.org> In-Reply-To: References: <20250110.152323-sassy.torch.lavish.rent-vKX3ul5B3qyi@cyphar.com> <20250114190521.0b69a1af64cac41106101154@kernel.org> <20250114112106.GC19816@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 14 Jan 2025 15:21:29 +0100 Jiri Olsa wrote: > On Tue, Jan 14, 2025 at 12:21:07PM +0100, Oleg Nesterov wrote: > > On 01/14, Masami Hiramatsu wrote: > > > > > > On Tue, 14 Jan 2025 10:22:20 +0100 > > > Jiri Olsa wrote: > > > > > > > @@ -418,6 +439,9 @@ SYSCALL_DEFINE0(uretprobe) > > > > regs->r11 = regs->flags; > > > > regs->cx = regs->ip; > > > > > > > > + /* zero rbx to signal trampoline that uretprobe syscall was executed */ > > > > + regs->bx = 0; > > > > > > Can we just return -ENOSYS as like as other syscall instead of > > > using rbx as a side channel? > > > We can carefully check the return address is not -ERRNO when set up > > > and reserve the -ENOSYS for this use case. > > > > Not sure I understand... > > > > But please not that the uretprobed function can return any value > > including -ENOSYS, and this is what sys_uretprobe() has to return. > > right, uretprobe syscall returns value of the uretprobed function, > so we can't use any reserved value We can make uretprobe (entry) fail if the return value is one of errno or NULL, because it *knows* what the return value here. Thank you, > > jirka -- Masami Hiramatsu (Google)