Re: [PATCH -next 0/5] fs: fix possible null-ptr-deref when parsing param

[Al Viro <viro@zeniv.linux.org.uk>]

On Mon, Oct 24, 2022 at 12:39:41AM +0800, Hawkins Jiawei wrote:
> According to commit "vfs: parse: deal with zero length string value",
> kernel will set the param->string to null pointer in vfs_parse_fs_string()
> if fs string has zero length.
> 
> Yet the problem is that, when fs parses its mount parameters, it will
> dereferences the param->string, without checking whether it is a
> null pointer, which may trigger a null-ptr-deref bug.
> 
> So this patchset reviews all functions for fs to parse parameters,
> by using `git grep -n "\.parse_param" fs/*`, and adds sanity check
> on param->string if its function will dereference param->string
> without check.

How about reverting the commit in question instead?  Or dropping it
from patch series, depending upon the way akpm handles the pile
these days...