pinctrl: renesas: checker: Limit cfg reg enum checks to provided IDs

[ Upstream commit 3803584 ]

If the number of provided enum IDs in a variable width config register
description does not match the expected number, the checker uses the
expected number for validating the individual enum IDs.

However, this may cause out-of-bounds accesses on the array holding the
enum IDs, leading to bogus enum_id conflict warnings.  Worse, if the bug
is an incorrect bit field description (e.g. accidentally using "12"
instead of "-12" for a reserved field), thousands of warnings may be
printed, overflowing the kernel log buffer.

Fix this by limiting the enum ID check to the number of provided enum
IDs.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/c7385f44f2faebb8856bcbb4e908d846fc1531fb.1705930809.git.geert+renesas@glider.be
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/pinctrl/renesas/core.c

@@ -909,9 +909,11 @@ static void __init sh_pfc_check_cfg_reg(const char *drvname,
 		sh_pfc_err("reg 0x%x: var_field_width declares %u instead of %u bits\n",
 			   cfg_reg->reg, rw, cfg_reg->reg_width);
 
-	if (n != cfg_reg->nr_enum_ids)
+	if (n != cfg_reg->nr_enum_ids) {
 		sh_pfc_err("reg 0x%x: enum_ids[] has %u instead of %u values\n",
 			   cfg_reg->reg, cfg_reg->nr_enum_ids, n);
+		n = cfg_reg->nr_enum_ids;
+	}
 
 check_enum_ids:
 	sh_pfc_check_reg_enums(drvname, cfg_reg->reg, cfg_reg->enum_ids, n);