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Code

efi: stmm: Fix incorrect buffer allocation method

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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 commit 9aec2fb0fd
("slab: allocate frozen pages"), though it was broken before as well.

Fix this by using alloc_pages_exact() instead of kmalloc().

Fixes: c44b6be62e ("efi: Add tee-based EFI variable driver")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Jan Kiszka 2025-08-25 18:07:10 +02:00 committed by Ard Biesheuvel
parent 8f5ae30d69
commit c5e81e6726
1 changed files with 12 additions and 9 deletions
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21
drivers/firmware/efi/stmm/tee_stmm_efi.c
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@ -143,6 +143,10 @@ static efi_status_t mm_communicate(u8 *comm_buf, size_t payload_size)
return var_hdr->ret_status; return var_hdr->ret_status;
} }
#define COMM_BUF_SIZE(__payload_size) (MM_COMMUNICATE_HEADER_SIZE + \
MM_VARIABLE_COMMUNICATE_SIZE + \
(__payload_size))
/** /**
* setup_mm_hdr() - Allocate a buffer for StandAloneMM and initialize the * setup_mm_hdr() - Allocate a buffer for StandAloneMM and initialize the
* header data. * header data.
@ -173,9 +177,8 @@ static void *setup_mm_hdr(u8 **dptr, size_t payload_size, size_t func,
return NULL; return NULL;
} }
comm_buf = kzalloc(MM_COMMUNICATE_HEADER_SIZE + comm_buf = alloc_pages_exact(COMM_BUF_SIZE(payload_size),
MM_VARIABLE_COMMUNICATE_SIZE + payload_size, GFP_KERNEL | __GFP_ZERO);
GFP_KERNEL);
if (!comm_buf) { if (!comm_buf) {
*ret = EFI_OUT_OF_RESOURCES; *ret = EFI_OUT_OF_RESOURCES;
return NULL; return NULL;
@ -239,7 +242,7 @@ static efi_status_t get_max_payload(size_t *size)
*/ */
*size -= 2; *size -= 2;
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }
@ -282,7 +285,7 @@ static efi_status_t get_property_int(u16 *name, size_t name_size,
memcpy(var_property, &smm_property->property, sizeof(*var_property)); memcpy(var_property, &smm_property->property, sizeof(*var_property));
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }
@ -347,7 +350,7 @@ static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
memcpy(data, (u8 *)var_acc->name + var_acc->name_size, memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
var_acc->data_size); var_acc->data_size);
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }
@ -404,7 +407,7 @@ static efi_status_t tee_get_next_variable(unsigned long *name_size,
memcpy(name, var_getnext->name, var_getnext->name_size); memcpy(name, var_getnext->name, var_getnext->name_size);
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }
@ -467,7 +470,7 @@ static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
ret = mm_communicate(comm_buf, payload_size); ret = mm_communicate(comm_buf, payload_size);
dev_dbg(pvt_data.dev, "Set Variable %s %d %lx\n", __FILE__, __LINE__, ret); dev_dbg(pvt_data.dev, "Set Variable %s %d %lx\n", __FILE__, __LINE__, ret);
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }
@ -507,7 +510,7 @@ static efi_status_t tee_query_variable_info(u32 attributes,
*max_variable_size = mm_query_info->max_variable_size; *max_variable_size = mm_query_info->max_variable_size;
out: out:
kfree(comm_buf); free_pages_exact(comm_buf, COMM_BUF_SIZE(payload_size));
return ret; return ret;
} }