linux-kernel - Re: [RFC PATCH] initramfs: Add size validation to prevent tmpfs exhaustion

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Message-ID: <20250318205139.71fe0c02.ddiss@suse.de>
Date: Tue, 18 Mar 2025 20:51:39 +1100
From: David Disseldorp <ddiss@...e.de>
To: Stephen Eta Zhou <stephen.eta.zhou@...look.com>
Cc: "jsperbeck@...gle.com" <jsperbeck@...gle.com>,
 "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
 "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
 "lukas@...ner.de" <lukas@...ner.de>, "wufan@...ux.microsoft.com"
 <wufan@...ux.microsoft.com>, "linux-kernel@...r.kernel.org"
 <linux-kernel@...r.kernel.org>, "linux-fsdevel@...r.kernel.org"
 <linux-fsdevel@...r.kernel.org>
Subject: Re: [RFC PATCH] initramfs: Add size validation to prevent tmpfs
 exhaustion

On Tue, 18 Mar 2025 06:28:53 +0000, Stephen Eta Zhou wrote:

> > There's room for improvement WRT how out-of-memory failures are reported  
> 
> I am currently trying to find a good optimization solution for this. Since initramfs is decompressed in the early stage of the kernel, if the decompression fails, it will call panic to put the kernel into a panic state.

Not always. The *built-in* initramfs unpack_to_rootfs() error path
panics, but external initramfs unpack_to_rootfs() failure won't panic
immediately...

> There is a contradiction: at this time, the console and serial port have not been initialized yet, which will cause the error message to fail to be output, resulting in a suspended state, and no valid output can be seen.

Are your console/serial drivers loaded as external modules? That sounds
like a configuration problem.