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[PATCH 1/2] virt: sev-guest: Allocate request data dynamically

Alexey Kardashevskiy posted 2 patches 11 months, 1 week ago
[PATCH 1/2] virt: sev-guest: Allocate request data dynamically
Posted by Alexey Kardashevskiy 11 months, 1 week ago 
From: Nikunj A Dadhania <nikunj@amd.com>

Commit ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command
mutex") narrowed the command mutex scope to snp_send_guest_request.
However, GET_REPORT, GET_DERIVED_KEY, and GET_EXT_REPORT share the req
structure in snp_guest_dev. Without the mutex protection, concurrent
requests can overwrite each other's data. Fix it by dynamically allocating
the request structure.

Fixes: ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command mutex")
Cc: stable@vger.kernel.org
Reported-by: andreas.stuehrk@yaxi.tech
Closes: https://github.com/AMDESE/AMDSEV/issues/265
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
---
 drivers/virt/coco/sev-guest/sev-guest.c | 24 ++++++++++++--------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index ddec5677e247..4699fdc9ed44 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -39,12 +39,6 @@ struct snp_guest_dev {
 	struct miscdevice misc;
 
 	struct snp_msg_desc *msg_desc;
-
-	union {
-		struct snp_report_req report;
-		struct snp_derived_key_req derived_key;
-		struct snp_ext_report_req ext_report;
-	} req;
 };
 
 /*
@@ -72,7 +66,7 @@ struct snp_req_resp {
 
 static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
-	struct snp_report_req *report_req = &snp_dev->req.report;
+	struct snp_report_req *report_req __free(kfree) = NULL;
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_report_resp *report_resp;
 	struct snp_guest_req req = {};
@@ -81,6 +75,10 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	if (!arg->req_data || !arg->resp_data)
 		return -EINVAL;
 
+	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
+	if (!report_req)
+		return -ENOMEM;
+
 	if (copy_from_user(report_req, (void __user *)arg->req_data, sizeof(*report_req)))
 		return -EFAULT;
 
@@ -117,7 +115,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 
 static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
-	struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
+	struct snp_derived_key_req *derived_key_req __free(kfree) = NULL;
 	struct snp_derived_key_resp derived_key_resp = {0};
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_guest_req req = {};
@@ -137,6 +135,10 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	if (sizeof(buf) < resp_len)
 		return -ENOMEM;
 
+	derived_key_req = kzalloc(sizeof(*derived_key_req), GFP_KERNEL_ACCOUNT);
+	if (!derived_key_req)
+		return -ENOMEM;
+
 	if (copy_from_user(derived_key_req, (void __user *)arg->req_data,
 			   sizeof(*derived_key_req)))
 		return -EFAULT;
@@ -169,7 +171,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 			  struct snp_req_resp *io)
 
 {
-	struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
+	struct snp_ext_report_req *report_req __free(kfree) = NULL;
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_report_resp *report_resp;
 	struct snp_guest_req req = {};
@@ -179,6 +181,10 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 	if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
 		return -EINVAL;
 
+	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
+	if (!report_req)
+		return -ENOMEM;
+
 	if (copy_from_sockptr(report_req, io->req_data, sizeof(*report_req)))
 		return -EFAULT;
 
-- 
2.47.1
Re: [PATCH 1/2] virt: sev-guest: Allocate request data dynamically
Posted by Alexey Kardashevskiy 11 months, 1 week ago 

On 7/3/25 12:36, Alexey Kardashevskiy wrote:
> From: Nikunj A Dadhania <nikunj@amd.com>
> 
> Commit ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command
> mutex") narrowed the command mutex scope to snp_send_guest_request.
> However, GET_REPORT, GET_DERIVED_KEY, and GET_EXT_REPORT share the req
> structure in snp_guest_dev. Without the mutex protection, concurrent
> requests can overwrite each other's data. Fix it by dynamically allocating
> the request structure.
> 
> Fixes: ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command mutex")
> Cc: stable@vger.kernel.org
> Reported-by: andreas.stuehrk@yaxi.tech
> Closes: https://github.com/AMDESE/AMDSEV/issues/265
> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>


oh. forgot:

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>




> ---
>   drivers/virt/coco/sev-guest/sev-guest.c | 24 ++++++++++++--------
>   1 file changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index ddec5677e247..4699fdc9ed44 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -39,12 +39,6 @@ struct snp_guest_dev {
>   	struct miscdevice misc;
>   
>   	struct snp_msg_desc *msg_desc;
> -
> -	union {
> -		struct snp_report_req report;
> -		struct snp_derived_key_req derived_key;
> -		struct snp_ext_report_req ext_report;
> -	} req;
>   };
>   
>   /*
> @@ -72,7 +66,7 @@ struct snp_req_resp {
>   
>   static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
>   {
> -	struct snp_report_req *report_req = &snp_dev->req.report;
> +	struct snp_report_req *report_req __free(kfree) = NULL;
>   	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
>   	struct snp_report_resp *report_resp;
>   	struct snp_guest_req req = {};
> @@ -81,6 +75,10 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
>   	if (!arg->req_data || !arg->resp_data)
>   		return -EINVAL;
>   
> +	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
> +	if (!report_req)
> +		return -ENOMEM;
> +
>   	if (copy_from_user(report_req, (void __user *)arg->req_data, sizeof(*report_req)))
>   		return -EFAULT;
>   
> @@ -117,7 +115,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
>   
>   static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
>   {
> -	struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
> +	struct snp_derived_key_req *derived_key_req __free(kfree) = NULL;
>   	struct snp_derived_key_resp derived_key_resp = {0};
>   	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
>   	struct snp_guest_req req = {};
> @@ -137,6 +135,10 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
>   	if (sizeof(buf) < resp_len)
>   		return -ENOMEM;
>   
> +	derived_key_req = kzalloc(sizeof(*derived_key_req), GFP_KERNEL_ACCOUNT);
> +	if (!derived_key_req)
> +		return -ENOMEM;
> +
>   	if (copy_from_user(derived_key_req, (void __user *)arg->req_data,
>   			   sizeof(*derived_key_req)))
>   		return -EFAULT;
> @@ -169,7 +171,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
>   			  struct snp_req_resp *io)
>   
>   {
> -	struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
> +	struct snp_ext_report_req *report_req __free(kfree) = NULL;
>   	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
>   	struct snp_report_resp *report_resp;
>   	struct snp_guest_req req = {};
> @@ -179,6 +181,10 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
>   	if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
>   		return -EINVAL;
>   
> +	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
> +	if (!report_req)
> +		return -ENOMEM;
> +
>   	if (copy_from_sockptr(report_req, io->req_data, sizeof(*report_req)))
>   		return -EFAULT;
>   

-- 
Alexey
[tip: x86/urgent] virt: sev-guest: Allocate request data dynamically
Posted by tip-bot2 for Nikunj A Dadhania 11 months, 1 week ago 
The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     ac7c06acaa3738b38e83815ac0f07140ad320f13
Gitweb:        https://git.kernel.org/tip/ac7c06acaa3738b38e83815ac0f07140ad320f13
Author:        Nikunj A Dadhania <nikunj@amd.com>
AuthorDate:    Thu, 06 Mar 2025 19:17:21 +11:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Fri, 07 Mar 2025 13:34:25 +01:00

virt: sev-guest: Allocate request data dynamically

Commit

  ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command mutex")

narrowed the command mutex scope to snp_send_guest_request().  However,
GET_REPORT, GET_DERIVED_KEY, and GET_EXT_REPORT share the req structure in
snp_guest_dev. Without the mutex protection, concurrent requests can overwrite
each other's data. Fix it by dynamically allocating the request structure.

Fixes: ae596615d93d ("virt: sev-guest: Reduce the scope of SNP command mutex")
Closes: https://github.com/AMDESE/AMDSEV/issues/265
Reported-by: andreas.stuehrk@yaxi.tech
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250307013700.437505-2-aik@amd.com
---
 drivers/virt/coco/sev-guest/sev-guest.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 264b652..23ac177 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -38,12 +38,6 @@ struct snp_guest_dev {
 	struct miscdevice misc;
 
 	struct snp_msg_desc *msg_desc;
-
-	union {
-		struct snp_report_req report;
-		struct snp_derived_key_req derived_key;
-		struct snp_ext_report_req ext_report;
-	} req;
 };
 
 /*
@@ -71,7 +65,7 @@ struct snp_req_resp {
 
 static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
-	struct snp_report_req *report_req = &snp_dev->req.report;
+	struct snp_report_req *report_req __free(kfree) = NULL;
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_report_resp *report_resp;
 	struct snp_guest_req req = {};
@@ -80,6 +74,10 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	if (!arg->req_data || !arg->resp_data)
 		return -EINVAL;
 
+	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
+	if (!report_req)
+		return -ENOMEM;
+
 	if (copy_from_user(report_req, (void __user *)arg->req_data, sizeof(*report_req)))
 		return -EFAULT;
 
@@ -116,7 +114,7 @@ e_free:
 
 static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
-	struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
+	struct snp_derived_key_req *derived_key_req __free(kfree) = NULL;
 	struct snp_derived_key_resp derived_key_resp = {0};
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_guest_req req = {};
@@ -136,6 +134,10 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	if (sizeof(buf) < resp_len)
 		return -ENOMEM;
 
+	derived_key_req = kzalloc(sizeof(*derived_key_req), GFP_KERNEL_ACCOUNT);
+	if (!derived_key_req)
+		return -ENOMEM;
+
 	if (copy_from_user(derived_key_req, (void __user *)arg->req_data,
 			   sizeof(*derived_key_req)))
 		return -EFAULT;
@@ -168,7 +170,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 			  struct snp_req_resp *io)
 
 {
-	struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
+	struct snp_ext_report_req *report_req __free(kfree) = NULL;
 	struct snp_msg_desc *mdesc = snp_dev->msg_desc;
 	struct snp_report_resp *report_resp;
 	struct snp_guest_req req = {};
@@ -178,6 +180,10 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 	if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
 		return -EINVAL;
 
+	report_req = kzalloc(sizeof(*report_req), GFP_KERNEL_ACCOUNT);
+	if (!report_req)
+		return -ENOMEM;
+
 	if (copy_from_sockptr(report_req, io->req_data, sizeof(*report_req)))
 		return -EFAULT;

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