RE: [PATCH] soc/fsl/qe: fix err handling of ucc_of_parse_tdm

[Qiang Zhao]

Hi Wen,

Will you send another version to resolve the issue described in the comments?

BR
Qiang

> -----Original Message-----
> From: Li Yang <leoyang.li@xxxxxxx>
> Sent: 2018å12æ6æ 4:10
> To: wang.yi59@xxxxxxxxxx
> Cc: Qiang Zhao <qiang.zhao@xxxxxxx>; zhong.weidong@xxxxxxxxxx; lkml
> <linux-kernel@xxxxxxxxxxxxxxx>; julia.lawall@xxxxxxx; linuxppc-dev
> <linuxppc-dev@xxxxxxxxxxxxxxxx>; wen.yang99@xxxxxxxxxx; moderated
> list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE
> <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
> Subject: Re: [PATCH] soc/fsl/qe: fix err handling of ucc_of_parse_tdm
> 
> On Thu, Nov 22, 2018 at 2:42 PM Yi Wang <wang.yi59@xxxxxxxxxx> wrote:
> >
> > From: Wen Yang <wen.yang99@xxxxxxxxxx>
> >
> > Currently there are 2 problems with the ucc_of_parse_tdm function:
> > 1,a possible null pointer dereference in ucc_of_parse_tdm, detected by
> > the semantic patch deref_null.cocci, with the following warning:
> > drivers/soc/fsl/qe/qe_tdm.c:177:21-24: ERROR: pdev is NULL but
> dereferenced.
> > 2,dev gets modified, so in any case that devm_iounmap() will fail even
> > when the new pdev is valid, because the iomap was done with a different
> pdev.
> > This patch fixes them.
> 
> While we are at this, I think this logic need more serious fixing.  I see there is
> no driver bind with the "fsl,t1040-qe-si" or "fsl,t1040-qe-siram" device.  So
> allocating resources using devm_*() with these devices won't provide a
> cleanup path for these resources when the caller fails.  I think we should
> probably allocate resource under device of caller (e.g. ucc-hdlc), so that when
> caller probe fails or is removed it will trigger the cleanup.
> 
> >
> > Suggested-by: Christophe LEROY <christophe.leroy@xxxxxx>
> > Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
> > CC: Julia Lawall <julia.lawall@xxxxxxx>
> > CC: Zhao Qiang <qiang.zhao@xxxxxxx>
> > ---
> >  drivers/soc/fsl/qe/qe_tdm.c | 20 ++++++++++----------
> >  1 file changed, 10 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/soc/fsl/qe/qe_tdm.c b/drivers/soc/fsl/qe/qe_tdm.c
> > index f78c346..9a29f0b 100644
> > --- a/drivers/soc/fsl/qe/qe_tdm.c
> > +++ b/drivers/soc/fsl/qe/qe_tdm.c
> > @@ -47,7 +47,7 @@ int ucc_of_parse_tdm(struct device_node *np, struct
> ucc_tdm *utdm,
> >         struct resource *res;
> >         struct device_node *np2;
> >         static int siram_init_flag;
> > -       struct platform_device *pdev;
> > +       struct platform_device *pdev_si, *pdev_siram;
> >
> >         sprop = of_get_property(np, "fsl,rx-sync-clock", NULL);
> >         if (sprop) {
> > @@ -129,16 +129,16 @@ int ucc_of_parse_tdm(struct device_node *np,
> struct ucc_tdm *utdm,
> >         if (!np2)
> >                 return -EINVAL;
> >
> > -       pdev = of_find_device_by_node(np2);
> > -       if (!pdev) {
> > +       pdev_si = of_find_device_by_node(np2);
> > +       if (!pdev_si) {
> >                 pr_err("%pOFn: failed to lookup pdev\n", np2);
> >                 of_node_put(np2);
> >                 return -EINVAL;
> >         }
> >
> >         of_node_put(np2);
> > -       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > -       utdm->si_regs = devm_ioremap_resource(&pdev->dev, res);
> > +       res = platform_get_resource(pdev_si, IORESOURCE_MEM, 0);
> > +       utdm->si_regs = devm_ioremap_resource(&pdev_si->dev, res);
> >         if (IS_ERR(utdm->si_regs)) {
> >                 ret = PTR_ERR(utdm->si_regs);
> >                 goto err_miss_siram_property; @@ -150,8 +150,8 @@
> int
> > ucc_of_parse_tdm(struct device_node *np, struct ucc_tdm *utdm,
> >                 goto err_miss_siram_property;
> >         }
> >
> > -       pdev = of_find_device_by_node(np2);
> > -       if (!pdev) {
> > +       pdev_siram = of_find_device_by_node(np2);
> > +       if (!pdev_siram) {
> >                 ret = -EINVAL;
> >                 pr_err("%pOFn: failed to lookup pdev\n", np2);
> >                 of_node_put(np2);
> > @@ -159,8 +159,8 @@ int ucc_of_parse_tdm(struct device_node *np, struct
> ucc_tdm *utdm,
> >         }
> >
> >         of_node_put(np2);
> > -       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > -       utdm->siram = devm_ioremap_resource(&pdev->dev, res);
> > +       res = platform_get_resource(pdev_siram, IORESOURCE_MEM, 0);
> > +       utdm->siram = devm_ioremap_resource(&pdev_siram->dev, res);
> >         if (IS_ERR(utdm->siram)) {
> >                 ret = PTR_ERR(utdm->siram);
> >                 goto err_miss_siram_property; @@ -174,7 +174,7 @@
> int
> > ucc_of_parse_tdm(struct device_node *np, struct ucc_tdm *utdm,
> >         return ret;
> >
> >  err_miss_siram_property:
> > -       devm_iounmap(&pdev->dev, utdm->si_regs);
> > +       devm_iounmap(&pdev_si->dev, utdm->si_regs);
> >         return ret;
> >  }
> >  EXPORT_SYMBOL(ucc_of_parse_tdm);
> > --
> > 2.9.5
> >