lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 21 Nov 2022 11:48:40 -0800
From:   Andrew Morton <>
To:     Alexander Potapenko <>
        Eric Biggers <>,
Subject: Re: [PATCH 1/5] fs: ext4: initialize fsdata in pagecache_write()

On Mon, 21 Nov 2022 12:21:30 +0100 Alexander Potapenko <> wrote:

> When aops->write_begin() does not initialize fsdata, KMSAN reports
> an error passing the latter to aops->write_end().
> Fix this by unconditionally initializing fsdata.
> ...

I'm assuming that this is not-a-bug, and that these changes are purely
workarounds for a KMSAN shortcoming?

If true, this important info should be included in each changelog,

If false, please provide a full description of the end-user visible
effects of the bug.

Also, it would be helpful to describe why it is not considered
practical to teach KMSAN to handle this?

> --- a/fs/ext4/verity.c
> +++ b/fs/ext4/verity.c
> @@ -79,7 +79,7 @@ static int pagecache_write(struct inode *inode, const void *buf, size_t count,
>  		size_t n = min_t(size_t, count,
>  				 PAGE_SIZE - offset_in_page(pos));
>  		struct page *page;
> -		void *fsdata;
> +		void *fsdata = NULL;
>  		int res;
>  		res = aops->write_begin(NULL, mapping, pos, n, &page, &fsdata);

Powered by blists - more mailing lists