Messages in this thread | | | Date | Fri, 15 Sep 2023 15:28:14 +0100 | From | Al Viro <> | Subject | Re: [PATCH 03/19] fs: release anon dev_t in deactivate_locked_super |
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On Fri, Sep 15, 2023 at 04:12:07PM +0200, Christian Brauner wrote: > + static void some_fs_kill_sb(struct super_block *sb) > + { > + struct some_fs_info *info = sb->s_fs_info; > + > + kill_*_super(sb); > + kfree(info); > + } > + > +It's best practice to never deviate from this pattern.
The last part is flat-out incorrect. If e.g. fatfs or cifs ever switches to that pattern, you'll get UAF - they need freeing of ->s_fs_info of anything that ever had been mounted done with RCU delay; moreover, unload_nls() in fatfs needs to be behind the same.
Lifetime rules for fs-private parts of superblock are really private to filesystem; their use by sget/sget_fc callbacks might impose restrictions on those, but that again is none of the VFS business.
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