[PATCH 01/10] pinctrl: sunxi: Fix out-of-bounds irq_bank index when first bank has no IRQs

[Lee Jones]

In prepare_function_table(), irq_bank and last_bank are initialised to 0
and last_bank is updated on every bank regardless of whether it supports
interrupts.  On SoCs where bank 0 (PA) has no pins or does not support
interrupts (such as Allwinner A523 and A733), the first IRQ-capable bank
has bank > 0, which causes irq_bank to be incremented to 1 instead of
starting at 0.  As a result, the final IRQ bank receives irq_bank equal
to desc->irq_banks and writes out-of-bounds past pctl->irq_array during
sunxi_pinctrl_build_state().

Initialise irq_bank and last_bank to -1 and only update last_bank when
processing an IRQ-capable bank so that irq_bank always starts at 0 and
increments sequentially across IRQ-capable banks.

Fixes: f5e2cd34b12f ("pinctrl: sunxi: allow reading mux values from DT")
Closes: https://sashiko.dev/#/bug/linux-9c4dd832-02d4-4096-9e91-a03c1d4d85b3
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
 drivers/pinctrl/sunxi/pinctrl-sunxi-dt.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi-dt.c b/drivers/pinctrl/sunxi/pinctrl-sunxi-dt.c
index 8bcd566593ae..79ca1a7c4837 100644
--- a/drivers/pinctrl/sunxi/pinctrl-sunxi-dt.c
+++ b/drivers/pinctrl/sunxi/pinctrl-sunxi-dt.c
@@ -208,8 +208,8 @@ static int prepare_function_table(struct device *dev, struct device_node *pnode,
 	 * Assign the function's memory and fill in GPIOs, IRQ and a sentinel.
 	 * The extra functions will be filled in later.
 	 */
-	irq_bank = 0;
-	last_bank = 0;
+	irq_bank = -1;
+	last_bank = -1;
 	for (i = 0; i < npins; i++) {
 		struct sunxi_desc_pin *pin = &pins[i];
 		int bank = (pin->pin.number - pin_base) / PINS_PER_BANK;
@@ -222,17 +222,16 @@ static int prepare_function_table(struct device *dev, struct device_node *pnode,
 		func[1].muxval = 1;
 
 		if (irq_mux) {
-			if (bank > last_bank)
+			if (bank > last_bank) {
 				irq_bank++;
+				last_bank = bank;
+			}
 			func[lastfunc].muxval = irq_mux;
 			func[lastfunc].irqbank = irq_bank;
 			func[lastfunc].irqnum = pin->pin.number % PINS_PER_BANK;
 			func[lastfunc].name = "irq";
 		}
 
-		if (bank > last_bank)
-			last_bank = bank;
-
 		pin->functions = func;
 
 		/* Skip over the other needed functions and the sentinel. */
-- 
2.56.0.385.gac671c819a-goog