linux-kernel - [PATCH] misc: amd-sbi: Address issues reported in smatch

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Message-ID: <20250530081158.121137-1-akshay.gupta@amd.com>
Date: Fri, 30 May 2025 13:41:58 +0530
From: Akshay Gupta <akshay.gupta@....com>
To: <linux-kernel@...r.kernel.org>
CC: <gregkh@...uxfoundation.org>, <arnd@...db.de>, <Anand.Umarji@....com>,
	Akshay Gupta <akshay.gupta@....com>, Dan Carpenter
	<dan.carpenter@...aro.org>, Naveen Krishna Chatradhi
	<naveenkrishna.chatradhi@....com>
Subject: [PATCH] misc: amd-sbi: Address issues 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'
drivers/misc/amd-sbi/rmi-core.c:376 apml_rmi_reg_xfer() warn: maybe return -EFAULT instead of the bytes remaining?
drivers/misc/amd-sbi/rmi-core.c:394 apml_mailbox_xfer() warn: maybe return -EFAULT instead of the bytes remaining?
drivers/misc/amd-sbi/rmi-core.c:411 apml_cpuid_xfer() warn: maybe return -EFAULT instead of the bytes remaining?
drivers/misc/amd-sbi/rmi-core.c:428 apml_mcamsr_xfer() warn: maybe return -EFAULT instead of the bytes remaining?

copy_to/from_user() returns number of bytes, not copied.
In case data not copied, return "-EFAULT".

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>
---
This patch is created on top of linux-next

 drivers/misc/amd-sbi/rmi-core.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/amd-sbi/rmi-core.c b/drivers/misc/amd-sbi/rmi-core.c
index b653a21a909e..9048517c088c 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) {
@@ -373,7 +372,8 @@ static int apml_rmi_reg_xfer(struct sbrmi_data *data,
 	mutex_unlock(&data->lock);
 
 	if (msg.rflag && !ret)
-		return copy_to_user(arg, &msg, sizeof(struct apml_reg_xfer_msg));
+		if (copy_to_user(arg, &msg, sizeof(struct apml_reg_xfer_msg)))
+			return -EFAULT;
 	return ret;
 }
 
@@ -391,7 +391,9 @@ static int apml_mailbox_xfer(struct sbrmi_data *data, struct apml_mbox_msg __use
 	if (ret && ret != -EPROTOTYPE)
 		return ret;
 
-	return copy_to_user(arg, &msg, sizeof(struct apml_mbox_msg));
+	if (copy_to_user(arg, &msg, sizeof(struct apml_mbox_msg)))
+		return -EFAULT;
+	return ret;
 }
 
 static int apml_cpuid_xfer(struct sbrmi_data *data, struct apml_cpuid_msg __user *arg)
@@ -408,7 +410,9 @@ static int apml_cpuid_xfer(struct sbrmi_data *data, struct apml_cpuid_msg __user
 	if (ret && ret != -EPROTOTYPE)
 		return ret;
 
-	return copy_to_user(arg, &msg, sizeof(struct apml_cpuid_msg));
+	if (copy_to_user(arg, &msg, sizeof(struct apml_cpuid_msg)))
+		return -EFAULT;
+	return ret;
 }
 
 static int apml_mcamsr_xfer(struct sbrmi_data *data, struct apml_mcamsr_msg __user *arg)
@@ -425,7 +429,9 @@ static int apml_mcamsr_xfer(struct sbrmi_data *data, struct apml_mcamsr_msg __us
 	if (ret && ret != -EPROTOTYPE)
 		return ret;
 
-	return copy_to_user(arg, &msg, sizeof(struct apml_mcamsr_msg));
+	if (copy_to_user(arg, &msg, sizeof(struct apml_mcamsr_msg)))
+		return -EFAULT;
+	return ret;
 }
 
 static long sbrmi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
-- 
2.34.1