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References: <20210105202126.2879650-1-trix@redhat.com> <20210105222559.GA4118247@ubuntu-m3-large-x86>
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From:   Steve French <smfrench@gmail.com>
Date:   Tue, 5 Jan 2021 22:11:41 -0600
Message-ID: <CAH2r5mu-C3v-Tuz5E8nAFepSiCyypvw0g4ctTt2fjx1vEb9a_A@mail.gmail.com>
Subject: Re: [PATCH] cifs: check pointer before freeing
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     trix@redhat.com, Steve French <sfrench@samba.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        =?UTF-8?Q?Aur=C3=A9lien_Aptel?= <aaptel@suse.com>,
        Paulo Alcantara <palcantara@suse.de>,
        CIFS <linux-cifs@vger.kernel.org>,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux@googlegroups.com
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merged into cifs-2.6.git for-next and added cc:stable

On Tue, Jan 5, 2021 at 5:08 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Tue, Jan 05, 2021 at 12:21:26PM -0800, trix@redhat.com wrote:
> > From: Tom Rix <trix@redhat.com>
> >
> > clang static analysis reports this problem
> >
> > dfs_cache.c:591:2: warning: Argument to kfree() is a constant address
> >   (18446744073709551614), which is not memory allocated by malloc()
> >         kfree(vi);
> >         ^~~~~~~~~
> >
> > In dfs_cache_del_vol() the volume info pointer 'vi' being freed
> > is the return of a call to find_vol().  The large constant address
> > is find_vol() returning an error.
> >
> > Add an error check to dfs_cache_del_vol() similar to the one done
> > in dfs_cache_update_vol().
> >
> > Fixes: 54be1f6c1c37 ("cifs: Add DFS cache routines")
> > Signed-off-by: Tom Rix <trix@redhat.com>
>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
>
> > ---
> >  fs/cifs/dfs_cache.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/cifs/dfs_cache.c b/fs/cifs/dfs_cache.c
> > index 6ad6ba5f6ebe..0fdb0de7ff86 100644
> > --- a/fs/cifs/dfs_cache.c
> > +++ b/fs/cifs/dfs_cache.c
> > @@ -1260,7 +1260,8 @@ void dfs_cache_del_vol(const char *fullpath)
> >       vi = find_vol(fullpath);
> >       spin_unlock(&vol_list_lock);
> >
> > -     kref_put(&vi->refcnt, vol_release);
> > +     if (!IS_ERR(vi))
> > +             kref_put(&vi->refcnt, vol_release);
> >  }
> >
> >  /**
> > --
> > 2.27.0
> >


-- 
Thanks,

Steve