Messages in this thread | | | From | Paul Moore <> | Date | Wed, 9 Nov 2022 15:13:40 -0500 | Subject | Re: [GIT PULL] LSM fixes for v6.1 (#1) |
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On Wed, Nov 9, 2022 at 9:38 AM Serge E. Hallyn <serge@hallyn.com> wrote: > On Mon, Oct 31, 2022 at 12:22:29PM -0700, Linus Torvalds wrote: > > On Mon, Oct 31, 2022 at 4:07 AM Paul Moore <paul@paul-moore.com> wrote: > > > > > > A single patch to the capabilities code to fix a potential memory leak > > > in the xattr allocation error handling. Please apply for v6.1-rcX. > > > > Pulled. > > > > However, I react to the strange test condition. Sure, it's > > pre-existing, but does it really make sense? > > > > It does > > > > + if (ret < 0 || !tmpbuf) { > > + size = ret; > > + goto out_free; > > + } > > > > and how the heck can 'tmpbuf' be NULL if vfs_getxattr_alloc() succeeded? > > I had to go through the history a bit - the !tmpbuf check was added > > https://www.spinics.net/lists/stable/msg463010.html > > because of a gcc warning. Perhaps there's a better way to tell gcc > that it can't remain NULL if ret was < 0 ?
Ooof, that's ugly, but thanks for digging it up. As it turns out I happen to be working on a patch for vfs_getxattr_alloc() to fix the return value type right now, but it looks like I'll leave that gcc hack in place ... although I might leave a comment about it so the next person doesn't have to wonder.
> > I think that's not only impossible in the first place, but if it *was* > > possible, then that > > > > size = ret; > > goto out_free; > > > > would be wrong, because this function would return success even if it > > wasn't successful. > > > > That whole "cast to int, and then cast back to size_t" also smells of > > some serious confusion in the return value handling. It looks to me > > like vfs_getxattr_alloc() fundamentally returns an 'int', not a > > 'ssize_t', just by looking at the ->get function. But it just all > > looks weird. > > > > So this code has all kinds of oddities. > > > > Linus
-- paul-moore.com
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