Re: [PATCH v2] ceph: fix variable dereferenced before check in ceph_umount_begin()

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On Tue, Jun 3, 2025 at 12:25 PM Alex Markuze <amarkuze@xxxxxxxxxx> wrote:
>
> Reviewed by: Alex Markuze <amarkuze@xxxxxxxxxx>
>
> On Mon, Jun 2, 2025 at 9:50 PM Viacheslav Dubeyko <slava@xxxxxxxxxxx> wrote:
> >
> > From: Viacheslav Dubeyko <Slava.Dubeyko@xxxxxxx>
> >
> > smatch warnings:
> > fs/ceph/super.c:1042 ceph_umount_begin() warn: variable dereferenced before check 'fsc' (see line 1041)
> >
> > vim +/fsc +1042 fs/ceph/super.c
> >
> > void ceph_umount_begin(struct super_block *sb)
> > {
> >         struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
> >
> >         doutc(fsc->client, "starting forced umount\n");
> >               ^^^^^^^^^^^
> > Dereferenced
> >
> >         if (!fsc)
> >             ^^^^
> > Checked too late.
> >
> >                 return;
> >         fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
> >         __ceph_umount_begin(fsc);
> > }
> >
> > The VFS guarantees that the superblock is still
> > alive when it calls into ceph via ->umount_begin().
> > Finally, we don't need to check the fsc and
> > it should be valid. This patch simply removes
> > the fsc check.
> >
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Closes: https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_r_202503280852.YDB3pxUY-2Dlkp-40intel.com_&d=DwIBAg&c=BSDicqBQBDjDI9RkVyTcHQ&r=q5bIm4AXMzc8NJu1_RGmnQ2fMWKq4Y4RAkElvUgSs00&m=Ud7uNdqBY_Z7LJ_oI4fwdhvxOYt_5Q58tpkMQgDWhV3199_TCnINFU28Esc0BaAH&s=QOKWZ9HKLyd6XCxW-AUoKiFFg9roId6LOM01202zAk0&e=
> > Signed-off-by: Viacheslav Dubeyko <Slava.Dubeyko@xxxxxxx>
> > ---
> >  fs/ceph/super.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> > index f3951253e393..68a6d434093f 100644
> > --- a/fs/ceph/super.c
> > +++ b/fs/ceph/super.c
> > @@ -1033,8 +1033,7 @@ void ceph_umount_begin(struct super_block *sb)
> >         struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
> >
> >         doutc(fsc->client, "starting forced umount\n");
> > -       if (!fsc)
> > -               return;
> > +
> >         fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
> >         __ceph_umount_begin(fsc);
> >  }
> > --
> > 2.49.0
> >
>

Applied with the Closes tag amended (Proofpoint URL).

Thanks,

                Ilya





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