[PATCH 9/9] serial: xuartps: Fix out-of-bounds access through DT alias
From: geert@linux-m68k.org (Geert Uytterhoeven)
Date: 2018-02-20 10:38:43
Also in:
linux-devicetree, linux-renesas-soc, linux-serial, lkml
Hi Michal, On Tue, Feb 20, 2018 at 11:22 AM, Michal Simek [off-list ref] wrote:
On 20.2.2018 10:40, Geert Uytterhoeven wrote:quoted
The cdns_uart_port[] 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. Fixes: 1f118c02a1819856 ("serial: xuartps: Fix out-of-bounds access through DT alias")I didn't find this sha1 - patch name is this one.
Bummer, I totally screwed up my scripting...
Fixes: 928e9263492069ee ("tty: xuartps: Initialize ports according to aliases")
quoted
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- drivers/tty/serial/xilinx_uartps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index b9b2bc76bcac606c..abcb4d09a2d866d0 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c@@ -1110,7 +1110,7 @@ static struct uart_port *cdns_uart_get_port(int id) struct uart_port *port; /* Try the given port id if failed use default method */ - if (cdns_uart_port[id].mapbase != 0) { + if (id < CDNS_UART_NR_PORTS && cdns_uart_port[id].mapbase != 0) { /* Find the next unused port */ for (id = 0; id < CDNS_UART_NR_PORTS; id++) if (cdns_uart_port[id].mapbase == 0)Below should be better fix for this driver.
I considered that, too, but...
quoted hunk ↗ jump to hunk
--- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c@@ -1109,6 +1109,9 @@ static struct uart_port *cdns_uart_get_port(int id) { struct uart_port *port; + if (id >= CDNS_UART_NR_PORTS) + return NULL; + /* Try the given port id if failed use default method */ if (cdns_uart_port[id].mapbase != 0) { /* Find the next unused port */@@ -1117,9 +1120,6 @@ static struct uart_port *cdns_uart_get_port(int id) break; } - if (id >= CDNS_UART_NR_PORTS) - return NULL; -
... the above check cannot be removed, as it is needed to support the loop above to find an unused port.
port = &cdns_uart_port[id];
/* At this point, we've got an empty uart_port struct,
initialize it */
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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