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Message-ID: <37ba67b97d55c49a7c6a1597f104b30b31a4a395.1755285161.git.jan.kiszka@siemens.com>
Date: Fri, 15 Aug 2025 21:12:39 +0200
From: Jan Kiszka <jan.kiszka@...mens.com>
To: Ard Biesheuvel <ardb@...nel.org>,
Masahisa Kojima <masahisa.kojima@...aro.org>,
Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc: linux-efi@...r.kernel.org,
linux-kernel@...r.kernel.org,
Sumit Garg <sumit.garg@...aro.org>,
Jens Wiklander <jens.wiklander@...aro.org>
Subject: [PATCH 1/3] efi: stmm: Fix incorrect buffer allocation method
From: Jan Kiszka <jan.kiszka@...mens.com>
The communication buffer allocated by setup_mm_hdr is later on passed to
tee_shm_register_kernel_buf. The latter expects those buffers to be
contiguous pages, but setup_mm_hdr just uses kmalloc. That can cause
various corruptions or BUGs, specifically since 9aec2fb0fd5e, though it
was broken before as well.
Fix this by using alloc_pages_exact instead of kmalloc.
Fixes: c44b6be62e8d ("efi: Add tee-based EFI variable driver")
Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---
drivers/firmware/efi/stmm/tee_stmm_efi.c | 44 +++++++++++++++---------
1 file changed, 27 insertions(+), 17 deletions(-)
diff --git a/drivers/firmware/efi/stmm/tee_stmm_efi.c b/drivers/firmware/efi/stmm/tee_stmm_efi.c
index f741ca279052..706ba095a4ba 100644
--- a/drivers/firmware/efi/stmm/tee_stmm_efi.c
+++ b/drivers/firmware/efi/stmm/tee_stmm_efi.c
@@ -148,13 +148,14 @@ static efi_status_t mm_communicate(u8 *comm_buf, size_t payload_size)
* header data.
*
* @dptr: pointer address to store allocated buffer
+ * @nr_pages: pointer address to store number of allocated pages
* @payload_size: payload size
* @func: standAloneMM function number
* @ret: EFI return code
* Return: pointer to corresponding StandAloneMM function buffer or NULL
*/
-static void *setup_mm_hdr(u8 **dptr, size_t payload_size, size_t func,
- efi_status_t *ret)
+static void *setup_mm_hdr(u8 **dptr, size_t *nr_pages, size_t payload_size,
+ size_t func, efi_status_t *ret)
{
const efi_guid_t mm_var_guid = EFI_MM_VARIABLE_GUID;
struct efi_mm_communicate_header *mm_hdr;
@@ -173,9 +174,12 @@ static void *setup_mm_hdr(u8 **dptr, size_t payload_size, size_t func,
return NULL;
}
- comm_buf = kzalloc(MM_COMMUNICATE_HEADER_SIZE +
- MM_VARIABLE_COMMUNICATE_SIZE + payload_size,
- GFP_KERNEL);
+ *nr_pages = roundup(MM_COMMUNICATE_HEADER_SIZE +
+ MM_VARIABLE_COMMUNICATE_SIZE + payload_size,
+ PAGE_SIZE) / PAGE_SIZE;
+
+ comm_buf = alloc_pages_exact(*nr_pages * PAGE_SIZE,
+ GFP_KERNEL | __GFP_ZERO);
if (!comm_buf) {
*ret = EFI_OUT_OF_RESOURCES;
return NULL;
@@ -205,13 +209,14 @@ static efi_status_t get_max_payload(size_t *size)
struct smm_variable_payload_size *var_payload = NULL;
size_t payload_size;
u8 *comm_buf = NULL;
+ size_t nr_pages;
efi_status_t ret;
if (!size)
return EFI_INVALID_PARAMETER;
payload_size = sizeof(*var_payload);
- var_payload = setup_mm_hdr(&comm_buf, payload_size,
+ var_payload = setup_mm_hdr(&comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE,
&ret);
if (!var_payload)
@@ -239,7 +244,7 @@ static efi_status_t get_max_payload(size_t *size)
*/
*size -= 2;
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
@@ -250,6 +255,7 @@ static efi_status_t get_property_int(u16 *name, size_t name_size,
struct smm_variable_var_check_property *smm_property;
size_t payload_size;
u8 *comm_buf = NULL;
+ size_t nr_pages;
efi_status_t ret;
memset(var_property, 0, sizeof(*var_property));
@@ -258,7 +264,7 @@ static efi_status_t get_property_int(u16 *name, size_t name_size,
return EFI_INVALID_PARAMETER;
smm_property = setup_mm_hdr(
- &comm_buf, payload_size,
+ &comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET, &ret);
if (!smm_property)
return EFI_OUT_OF_RESOURCES;
@@ -282,7 +288,7 @@ static efi_status_t get_property_int(u16 *name, size_t name_size,
memcpy(var_property, &smm_property->property, sizeof(*var_property));
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
@@ -296,6 +302,7 @@ static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
size_t name_size;
size_t tmp_dsize;
u8 *comm_buf = NULL;
+ size_t nr_pages;
efi_status_t ret;
if (!name || !vendor || !data_size)
@@ -314,7 +321,7 @@ static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
}
payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + tmp_dsize;
- var_acc = setup_mm_hdr(&comm_buf, payload_size,
+ var_acc = setup_mm_hdr(&comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_GET_VARIABLE, &ret);
if (!var_acc)
return EFI_OUT_OF_RESOURCES;
@@ -347,7 +354,7 @@ static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
var_acc->data_size);
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
@@ -359,6 +366,7 @@ static efi_status_t tee_get_next_variable(unsigned long *name_size,
size_t out_name_size;
size_t in_name_size;
u8 *comm_buf = NULL;
+ size_t nr_pages;
efi_status_t ret;
if (!name_size || !name || !guid)
@@ -379,7 +387,7 @@ static efi_status_t tee_get_next_variable(unsigned long *name_size,
max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE;
payload_size = MM_VARIABLE_GET_NEXT_HEADER_SIZE + out_name_size;
- var_getnext = setup_mm_hdr(&comm_buf, payload_size,
+ var_getnext = setup_mm_hdr(&comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME,
&ret);
if (!var_getnext)
@@ -404,7 +412,7 @@ static efi_status_t tee_get_next_variable(unsigned long *name_size,
memcpy(name, var_getnext->name, var_getnext->name_size);
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
@@ -418,6 +426,7 @@ static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
size_t payload_size;
size_t name_size;
u8 *comm_buf = NULL;
+ size_t nr_pages;
if (!name || name[0] == 0 || !vendor)
return EFI_INVALID_PARAMETER;
@@ -436,7 +445,7 @@ static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
* so we won't need to account for any failures in reading/setting
* the properties, if the allocation fails
*/
- var_acc = setup_mm_hdr(&comm_buf, payload_size,
+ var_acc = setup_mm_hdr(&comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
if (!var_acc)
return EFI_OUT_OF_RESOURCES;
@@ -467,7 +476,7 @@ static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
ret = mm_communicate(comm_buf, payload_size);
dev_dbg(pvt_data.dev, "Set Variable %s %d %lx\n", __FILE__, __LINE__, ret);
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
@@ -489,9 +498,10 @@ static efi_status_t tee_query_variable_info(u32 attributes,
size_t payload_size;
efi_status_t ret;
u8 *comm_buf;
+ size_t nr_pages;
payload_size = sizeof(*mm_query_info);
- mm_query_info = setup_mm_hdr(&comm_buf, payload_size,
+ mm_query_info = setup_mm_hdr(&comm_buf, &nr_pages, payload_size,
SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO,
&ret);
if (!mm_query_info)
@@ -507,7 +517,7 @@ static efi_status_t tee_query_variable_info(u32 attributes,
*max_variable_size = mm_query_info->max_variable_size;
out:
- kfree(comm_buf);
+ free_pages_exact(comm_buf, nr_pages * PAGE_SIZE);
return ret;
}
--
2.43.0
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