The function efi_query_variable_store() may be invoked by efivar_entry_set_nonblocking(), which itself takes care to only call a non-blocking version of the SetVariable() runtime wrapper. However, efi_query_variable_store() may call the SetVariable() wrapper directly, as well as the wrapper for QueryVariableInfo(), both of which could deadlock in the same way we are trying to prevent by calling efivar_entry_set_nonblocking() in the first place.
So instead, modify efi_query_variable_store() to use the non-blocking variants of both SetVariable() and QueryVariableInfo() if invoked with the 'nonblocking' argument set to true. Signed-off-by: Ard Biesheuvel <[email protected]> --- arch/x86/platform/efi/quirks.c | 37 ++++++++++++++------ drivers/firmware/efi/vars.c | 16 +++++++-- include/linux/efi.h | 12 +++++-- 3 files changed, 49 insertions(+), 16 deletions(-) diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 1c7380da65ff..cbe542f5c75d 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -60,16 +60,27 @@ void efi_delete_dummy_variable(void) * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable * store. */ -efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) +efi_status_t efi_query_variable_store(u32 attributes, unsigned long size, + bool nonblocking) { efi_status_t status; u64 storage_size, remaining_size, max_size; + efi_set_variable_t *set_variable; + efi_query_variable_info_t *query_variable_info; if (!(attributes & EFI_VARIABLE_NON_VOLATILE)) return 0; - status = efi.query_variable_info(attributes, &storage_size, - &remaining_size, &max_size); + if (nonblocking) { + set_variable = efi.set_variable_nonblocking; + query_variable_info = efi.query_variable_info_nonblocking; + } else { + set_variable = efi.set_variable; + query_variable_info = efi.query_variable_info; + } + + status = query_variable_info(attributes, &storage_size, + &remaining_size, &max_size); if (status != EFI_SUCCESS) return status; @@ -92,18 +103,22 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) if (!dummy) return EFI_OUT_OF_RESOURCES; - status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID, - EFI_VARIABLE_NON_VOLATILE | - EFI_VARIABLE_BOOTSERVICE_ACCESS | - EFI_VARIABLE_RUNTIME_ACCESS, - dummy_size, dummy); + status = set_variable(efi_dummy_name, &EFI_DUMMY_GUID, + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + dummy_size, dummy); if (status == EFI_SUCCESS) { /* * This should have failed, so if it didn't make sure * that we delete it... */ - efi_delete_dummy_variable(); + set_variable(efi_dummy_name, &EFI_DUMMY_GUID, + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + 0, NULL); } kfree(dummy); @@ -112,8 +127,8 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) * The runtime code may now have triggered a garbage collection * run, so check the variable info again */ - status = efi.query_variable_info(attributes, &storage_size, - &remaining_size, &max_size); + status = query_variable_info(attributes, &storage_size, + &remaining_size, &max_size); if (status != EFI_SUCCESS) return status; diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 70a0fb10517f..d2a49626a335 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -234,7 +234,18 @@ check_var_size(u32 attributes, unsigned long size) if (!fops->query_variable_store) return EFI_UNSUPPORTED; - return fops->query_variable_store(attributes, size); + return fops->query_variable_store(attributes, size, false); +} + +static efi_status_t +check_var_size_nonblocking(u32 attributes, unsigned long size) +{ + const struct efivar_operations *fops = __efivars->ops; + + if (!fops->query_variable_store) + return EFI_UNSUPPORTED; + + return fops->query_variable_store(attributes, size, true); } static int efi_status_to_err(efi_status_t status) @@ -615,7 +626,8 @@ efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, if (!spin_trylock_irqsave(&__efivars->lock, flags)) return -EBUSY; - status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); + status = check_var_size_nonblocking(attributes, + size + ucs2_strsize(name, 1024)); if (status != EFI_SUCCESS) { spin_unlock_irqrestore(&__efivars->lock, flags); return -ENOSPC; diff --git a/include/linux/efi.h b/include/linux/efi.h index ad1e177ba48e..09f1559e7525 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -525,7 +525,9 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules, unsigned long count, u64 *max_size, int *reset_type); -typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long size); +typedef efi_status_t efi_query_variable_store_t(u32 attributes, + unsigned long size, + bool nonblocking); void efi_native_runtime_setup(void); @@ -881,13 +883,17 @@ extern void efi_enter_virtual_mode (void); /* switch EFI to virtual mode, if pos #ifdef CONFIG_X86 extern void efi_late_init(void); extern void efi_free_boot_services(void); -extern efi_status_t efi_query_variable_store(u32 attributes, unsigned long size); +extern efi_status_t efi_query_variable_store(u32 attributes, + unsigned long size, + bool nonblocking); extern void efi_find_mirror(void); #else static inline void efi_late_init(void) {} static inline void efi_free_boot_services(void) {} -static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned long size) +static inline efi_status_t efi_query_variable_store(u32 attributes, + unsigned long size, + bool nonblocking) { return EFI_SUCCESS; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
