linux-kernel - [PATCH] char: tpm: tpm-buf: Fix uninitialized return values in read helpers

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Message-Id: <20250409205536.210202-1-purvayeshi550@gmail.com>
Date: Thu, 10 Apr 2025 02:25:36 +0530
From: Purva Yeshi <purvayeshi550@...il.com>
To: peterhuewe@....de,
	jarkko@...nel.org
Cc: jgg@...pe.ca,
	linux-integrity@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Purva Yeshi <purvayeshi550@...il.com>
Subject: [PATCH] char: tpm: tpm-buf: Fix uninitialized return values in read helpers

Fix Smatch-detected error:
drivers/char/tpm/tpm-buf.c:208 tpm_buf_read_u8() error:
uninitialized symbol 'value'.
drivers/char/tpm/tpm-buf.c:225 tpm_buf_read_u16() error:
uninitialized symbol 'value'.
drivers/char/tpm/tpm-buf.c:242 tpm_buf_read_u32() error:
uninitialized symbol 'value'.

Call tpm_buf_read() to populate value but do not check its return
status. If the read fails, value remains uninitialized, causing
undefined behavior when returned or processed.

Initialize value to zero to ensure a defined return even if
tpm_buf_read() fails, avoiding undefined behavior from using
an uninitialized variable.

Signed-off-by: Purva Yeshi <purvayeshi550@...il.com>
---
 drivers/char/tpm/tpm-buf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index e49a19fea3bd..dc882fc9fa9e 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -201,7 +201,7 @@ static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void
  */
 u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset)
 {
-	u8 value;
+	u8 value = 0;

 	tpm_buf_read(buf, offset, sizeof(value), &value);

@@ -218,7 +218,7 @@ EXPORT_SYMBOL_GPL(tpm_buf_read_u8);
  */
 u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset)
 {
-	u16 value;
+	u16 value = 0;

 	tpm_buf_read(buf, offset, sizeof(value), &value);

@@ -235,7 +235,7 @@ EXPORT_SYMBOL_GPL(tpm_buf_read_u16);
  */
 u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
 {
-	u32 value;
+	u32 value = 0;

 	tpm_buf_read(buf, offset, sizeof(value), &value);

-- 
2.34.1