[v1] ACPI: APEI: EINJ: prevent memory corruption in error_type_set()

[PATCH next] ACPI: APEI: EINJ: prevent memory corruption in error_type_set()

Posted by Dan Carpenter 3 months, 2 weeks ago

The "einj_buf" buffer is 32 chars.  Verify that "count" is not too large
for that.  Also leave the last character as a NUL terminator to ensure
the string is properly terminated.

Fixes: 0c6176e1e186 ("ACPI: APEI: EINJ: Enable the discovery of EINJv2 capabilities")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 drivers/acpi/apei/einj-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/apei/einj-core.c b/drivers/acpi/apei/einj-core.c
index d6d7e36e3647..e77c0d4b4ee5 100644
--- a/drivers/acpi/apei/einj-core.c
+++ b/drivers/acpi/apei/einj-core.c
@@ -826,8 +826,11 @@ static ssize_t error_type_set(struct file *file, const char __user *buf,
 	int rc;
 	u64 val;
 
+	if (count > sizeof(einj_buf))
+		return -EINVAL;
+
 	memset(einj_buf, 0, sizeof(einj_buf));
-	if (copy_from_user(einj_buf, buf, count))
+	if (copy_from_user(einj_buf, buf, min(count, sizeof((einj_buf) - 1))))
 		return -EFAULT;
 
 	if (strncmp(einj_buf, "V2_", 3) == 0) {
-- 
2.47.2

Re: [PATCH next] ACPI: APEI: EINJ: prevent memory corruption in error_type_set()

Posted by Dan Carpenter 3 months, 2 weeks ago

On Wed, Jun 25, 2025 at 10:23:26AM -0500, Dan Carpenter wrote:
> The "einj_buf" buffer is 32 chars.  Verify that "count" is not too large
> for that.  Also leave the last character as a NUL terminator to ensure
> the string is properly terminated.
> 
> Fixes: 0c6176e1e186 ("ACPI: APEI: EINJ: Enable the discovery of EINJv2 capabilities")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
>  drivers/acpi/apei/einj-core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/apei/einj-core.c b/drivers/acpi/apei/einj-core.c
> index d6d7e36e3647..e77c0d4b4ee5 100644
> --- a/drivers/acpi/apei/einj-core.c
> +++ b/drivers/acpi/apei/einj-core.c
> @@ -826,8 +826,11 @@ static ssize_t error_type_set(struct file *file, const char __user *buf,
>  	int rc;
>  	u64 val;
>  
> +	if (count > sizeof(einj_buf))
> +		return -EINVAL;
> +
>  	memset(einj_buf, 0, sizeof(einj_buf));
> -	if (copy_from_user(einj_buf, buf, count))
> +	if (copy_from_user(einj_buf, buf, min(count, sizeof((einj_buf) - 1))))

Nope.  I put the parentheses in the wrong place...  Let me resend.

regards,
dan carpenter