[7/9] serial: sh-sci: Fix out-of-bounds access through DT alias

Message ID 1519119624-1268-8-git-send-email-geert+renesas@glider.be
State New
Headers show
Series
  • serial: Fix out-of-bounds accesses through DT aliases
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Commit Message

Geert Uytterhoeven Feb. 20, 2018, 9:40 a.m.
The sci_ports[] array is indexed using a value derived from the
"serialN" alias in DT, which may lead to an out-of-bounds access.

Fix this by adding a range check.

Note that the array size is defined by a Kconfig symbol
(CONFIG_SERIAL_SH_SCI_NR_UARTS), so this can even be triggered using a
legitimate DTB.

Fixes: f650cdf1c115498e ("serial: sh-sci: Fix out-of-bounds access through DT alias")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/tty/serial/sh-sci.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Geert Uytterhoeven Feb. 20, 2018, 10:53 a.m. | #1
On Tue, Feb 20, 2018 at 10:40 AM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> The sci_ports[] array is indexed using a value derived from the
> "serialN" alias in DT, which may lead to an out-of-bounds access.
>
> Fix this by adding a range check.
>
> Note that the array size is defined by a Kconfig symbol
> (CONFIG_SERIAL_SH_SCI_NR_UARTS), so this can even be triggered using a
> legitimate DTB.
>
> Fixes: f650cdf1c115498e ("serial: sh-sci: Fix out-of-bounds access through DT alias")

Fixes: 97ed9790c514066b ("serial: sh-sci: Remove unused platform data
capabilities field")

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

Patch

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 4d14f321cbec95e0..0fb4784860da6188 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -3620,6 +3620,10 @@  static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
 		dev_err(&pdev->dev, "failed to get alias id (%d)\n", id);
 		return NULL;
 	}
+	if (id >= SCI_NPORTS) {
+		dev_err(&pdev->dev, "serial%d out of range\n", id);
+		return NULL;
+	}
 
 	sp = &sci_ports[id];
 	*dev_id = id;