patch "firmware: xilinx: fix out-of-bounds access" added to char-misc-linus

This is a note to let you know that I've just added the patch titled

firmware: xilinx: fix out-of-bounds access

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From f3217d6f2f7a76b36a3326ad58c8897f4d5fbe31 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <[email protected]>
Date: Mon, 26 Oct 2020 16:54:36 +0100
Subject: firmware: xilinx: fix out-of-bounds access

The zynqmp_pm_set_suspend_mode() and zynqmp_pm_get_trustzone_version() functions pass values as api_id into zynqmp_pm_invoke_fn that are beyond PM_API_MAX, resulting in an out-of-bounds access:

drivers/firmware/xilinx/zynqmp.c: In function 'zynqmp_pm_set_suspend_mode':
drivers/firmware/xilinx/zynqmp.c:150:24: warning: array subscript 2562 is above array bounds of 'u32[64]' {aka 'unsigned int[64]'} [-Warray-bounds]
150 | if (zynqmp_pm_features[api_id] != PM_FEATURE_UNCHECKED)

      |      ~~~~~~~~~~~~~~~~~~^~~~~~~~
drivers/firmware/xilinx/zynqmp.c:28:12: note: while referencing 'zynqmp_pm_features'
   28 | static u32 zynqmp_pm_features[PM_API_MAX];
      |            ^~~~~~~~~~~~~~~~~~

Replace the resulting undefined behavior with an error return. This may break some things that happen to work at the moment but seems better than randomly overwriting kernel data.

I assume we need additional fixes for the two functions that now return an error.

---
 drivers/firmware/xilinx/zynqmp.c | 3 +++
 1 file changed, 3 insertions(+)

index 8d1ff2454e2e..efb8a66efc68 100644
@@ -147,6 +147,9 @@ static int zynqmp_pm_feature(u32 api_id)
 		return 0;
 
 	/* Return value if feature is already checked */
+	if (api_id > ARRAY_SIZE(zynqmp_pm_features))
+		return PM_FEATURE_INVALID;
+
 	if (zynqmp_pm_features[api_id] != PM_FEATURE_UNCHECKED)
 		return zynqmp_pm_features[api_id];
 

2.29.2