Commit ac7c06ac authored by Nikunj A Dadhania's avatar Nikunj A Dadhania Committed by Borislav Petkov (AMD)
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virt: sev-guest: Allocate request data dynamically 

Commit

  ae596615 ("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: ae596615 ("virt: sev-guest: Reduce the scope of SNP command mutex")
Closes: https://github.com/AMDESE/AMDSEV/issues/265


Reported-by: default avatar <andreas.stuehrk@yaxi.tech>
Signed-off-by: default avatarNikunj A Dadhania <nikunj@amd.com>
Signed-off-by: default avatarAlexey Kardashevskiy <aik@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250307013700.437505-2-aik@amd.com
parent 14cb5d83

drivers/virt/coco/sev-guest/sev-guest.c

+15 −9
Original line number Diff line number Diff line
@@ -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 @@ 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 = {};
@@ -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;