linux-kernel - [PATCH v3 1/2] misc: amd-sbi: Address potential integer overflow issue reported in smatch

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Message-ID: <20250701054041.373358-1-akshay.gupta@amd.com>
Date: Tue, 1 Jul 2025 05:40:40 +0000
From: Akshay Gupta <akshay.gupta@....com>
To: <linux-kernel@...r.kernel.org>
CC: <gregkh@...uxfoundation.org>, <arnd@...db.de>, <shyam-sundar.s-k@....com>,
	<gautham.shenoy@....com>, <mario.limonciello@....com>,
	<naveenkrishna.chatradhi@....com>, <anand.umarji@....com>, Akshay Gupta
	<akshay.gupta@....com>, Dan Carpenter <dan.carpenter@...aro.org>
Subject: [PATCH v3 1/2] misc: amd-sbi: Address potential integer overflow issue reported in smatch

Smatch warnings are reported for below commit,

Commit bb13a84ed6b7 ("misc: amd-sbi: Add support for CPUID protocol")
from Apr 28, 2025 (linux-next), leads to the following Smatch static
checker warning:

drivers/misc/amd-sbi/rmi-core.c:132 rmi_cpuid_read() warn: bitwise OR is zero '0xffffffff00000000 & 0xffff'
drivers/misc/amd-sbi/rmi-core.c:132 rmi_cpuid_read() warn: potential integer overflow from user 'msg->cpu_in_out << 32'
drivers/misc/amd-sbi/rmi-core.c:213 rmi_mca_msr_read() warn: bitwise OR is zero '0xffffffff00000000 & 0xffff'
drivers/misc/amd-sbi/rmi-core.c:213 rmi_mca_msr_read() warn: potential integer overflow from user 'msg->mcamsr_in_out << 32'

CPUID thread data from input is available at byte 4 & 5, this
patch fixes to copy the user data correctly in the argument.

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/all/aDVyO8ByVsceybk9@stanley.mountain/
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>
Signed-off-by: Akshay Gupta <akshay.gupta@....com>
---
Changes from v1:
 - Split patch as per Greg's suggestion

 drivers/misc/amd-sbi/rmi-core.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/amd-sbi/rmi-core.c b/drivers/misc/amd-sbi/rmi-core.c
index b653a21a909e..3570f3b269a9 100644
--- a/drivers/misc/amd-sbi/rmi-core.c
+++ b/drivers/misc/amd-sbi/rmi-core.c
@@ -42,7 +42,6 @@
 #define RD_MCA_CMD	0x86
 
 /* CPUID MCAMSR mask & index */
-#define CPUID_MCA_THRD_MASK	GENMASK(15, 0)
 #define CPUID_MCA_THRD_INDEX	32
 #define CPUID_MCA_FUNC_MASK	GENMASK(31, 0)
 #define CPUID_EXT_FUNC_INDEX	56
@@ -129,7 +128,7 @@ static int rmi_cpuid_read(struct sbrmi_data *data,
 		goto exit_unlock;
 	}
 
-	thread = msg->cpu_in_out << CPUID_MCA_THRD_INDEX & CPUID_MCA_THRD_MASK;
+	thread = msg->cpu_in_out >> CPUID_MCA_THRD_INDEX;
 
 	/* Thread > 127, Thread128 CS register, 1'b1 needs to be set to 1 */
 	if (thread > 127) {
@@ -210,7 +209,7 @@ static int rmi_mca_msr_read(struct sbrmi_data *data,
 		goto exit_unlock;
 	}
 
-	thread = msg->mcamsr_in_out << CPUID_MCA_THRD_INDEX & CPUID_MCA_THRD_MASK;
+	thread = msg->mcamsr_in_out >> CPUID_MCA_THRD_INDEX;
 
 	/* Thread > 127, Thread128 CS register, 1'b1 needs to be set to 1 */
 	if (thread > 127) {
-- 
2.25.1