Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 8 Oct 2018 15:12:02 +0200 | Subject | Re: [PATCH] reset: Fix potential use-after-free in __of_reset_control_get() |
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Hi Philipp,
On Mon, Oct 8, 2018 at 2:56 PM Philipp Zabel <p.zabel@pengutronix.de> wrote: > On Mon, 2018-10-08 at 13:14 +0200, Geert Uytterhoeven wrote: > > Calling of_node_put() decreases the reference count of a device tree > > object, and may free some data. > > > > However, the of_phandle_args structure embedding it is passed to > > reset_controller_dev.of_xlate() after that, so it may still be accessed. > > > > Move the call to of_node_put() down to fix this. > > > > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > > --- > > drivers/reset/core.c | 15 ++++++++------- > > 1 file changed, 8 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/reset/core.c b/drivers/reset/core.c > > index 225e34c56b94a2e3..bc9df10d31b4bae1 100644 > > --- a/drivers/reset/core.c > > +++ b/drivers/reset/core.c > > @@ -496,27 +496,28 @@ struct reset_control *__of_reset_control_get(struct device_node *node, > > break; > > } > > } > > - of_node_put(args.np); > > > > if (!rcdev) { > > - mutex_unlock(&reset_list_mutex); > > - return ERR_PTR(-EPROBE_DEFER); > > + rstc = ERR_PTR(-EPROBE_DEFER); > > + goto out; > > } > > > > if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { > > - mutex_unlock(&reset_list_mutex); > > - return ERR_PTR(-EINVAL); > > + rstc = ERR_PTR(-EINVAL); > > + goto out; > > } > > > > rstc_id = rcdev->of_xlate(rcdev, &args); > > if (rstc_id < 0) { > > - mutex_unlock(&reset_list_mutex); > > - return ERR_PTR(rstc_id); > > + rstc = ERR_PTR(rstc_id); > > + goto out; > > } > > > > /* reset_list_mutex also protects the rcdev's reset_control list */ > > rstc = __reset_control_get_internal(rcdev, rstc_id, shared); > > > > +out: > > + of_node_put(args.np); > > mutex_unlock(&reset_list_mutex); > > Thank you for the patch. I'd like to move of_node_put after mutex_unlock > for symmetry. If you agree, I can switch the two when applying.
No objection, thanks!
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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