linux-kernel - Re: Re: [PATCH] filemap: Init the newly allocated folio memory to 0 for the filemap

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Message-ID: <20240801052837.3388478-1-lizhi.xu@windriver.com>
Date: Thu, 1 Aug 2024 13:28:37 +0800
From: Lizhi Xu <lizhi.xu@...driver.com>
To: <viro@...iv.linux.org.uk>
CC: <brauner@...nel.org>, <jack@...e.cz>, <linux-fsdevel@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lizhi.xu@...driver.com>,
        <phillip@...ashfs.org.uk>, <squashfs-devel@...ts.sourceforge.net>,
        <syzbot+24ac24ff58dc5b0d26b9@...kaller.appspotmail.com>,
        <syzkaller-bugs@...glegroups.com>
Subject: Re: Re: [PATCH] filemap: Init the newly allocated folio memory to 0 for the filemap

> > syzbot report KMSAN: uninit-value in pick_link, this is because the
> > corresponding folio was not found from the mapping, and the memory was
> > not initialized when allocating a new folio for the filemap.
> >
> > To avoid the occurrence of kmsan report uninit-value, initialize the
> > newly allocated folio memory to 0.
> 
> NAK.
> 
> You are papering over the real bug here.
Did you see the splat? I think you didn't see that.
> 
> That page either
> 	* has been returned by find_get_page(), cached, uptodate and
> with uninitialized contents or
> 	* has been returned by successful read_mapping_page() - and
> left with uninitialized contents or
> 	* had inode->i_size in excess of initialized contents.
> 
> I'd suggest bisecting that.