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ACPI fixes for v4.12-rc6

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- Revert a 4.11 ACPICA change that made assumptions which are not
    satisfied on some systems and caused the enumeration of resources
    to fail on them (Rafael Wysocki).
 
  - Add a mechanism to prevent tables from being unmapped prematurely
    due to reference counter overflows (Lv Zheng).
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Merge tag 'acpi-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI fixes from Rafael Wysocki:
 "These revert an ACPICA commit from the 4.11 cycle that causes problems
  to happen on some systems and add a protection against possible kernel
  crashes due to table reference counter imbalance.

  Specifics:

   - Revert a 4.11 ACPICA change that made assumptions which are not
     satisfied on some systems and caused the enumeration of resources
     to fail on them (Rafael Wysocki).

   - Add a mechanism to prevent tables from being unmapped prematurely
     due to reference counter overflows (Lv Zheng)"

* tag 'acpi-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Tables: Mechanism to handle late stage acpi_get_table() imbalance
  Revert "ACPICA: Disassembler: Enhance resource descriptor detection"
This commit is contained in:
Linus Torvalds 2017-06-15 17:51:19 +09:00
commit 35e60a6b75
3 changed files with 39 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
drivers/acpi/acpica/tbutils.c
View File

@ -416,9 +416,18 @@ acpi_tb_get_table(struct acpi_table_desc *table_desc,
}
}
table_desc->validation_count++;
if (table_desc->validation_count == 0) {
table_desc->validation_count--;
if (table_desc->validation_count < ACPI_MAX_TABLE_VALIDATIONS) {
table_desc->validation_count++;
/*
* Detect validation_count overflows to ensure that the warning
* message will only be printed once.
*/
if (table_desc->validation_count >= ACPI_MAX_TABLE_VALIDATIONS) {
ACPI_WARNING((AE_INFO,
"Table %p, Validation count overflows\n",
table_desc));
}
}
*out_table = table_desc->pointer;
@ -445,13 +454,20 @@ void acpi_tb_put_table(struct acpi_table_desc *table_desc)
ACPI_FUNCTION_TRACE(acpi_tb_put_table);
if (table_desc->validation_count == 0) {
ACPI_WARNING((AE_INFO,
"Table %p, Validation count is zero before decrement\n",
table_desc));
return_VOID;
if (table_desc->validation_count < ACPI_MAX_TABLE_VALIDATIONS) {
table_desc->validation_count--;
/*
* Detect validation_count underflows to ensure that the warning
* message will only be printed once.
*/
if (table_desc->validation_count >= ACPI_MAX_TABLE_VALIDATIONS) {
ACPI_WARNING((AE_INFO,
"Table %p, Validation count underflows\n",
table_desc));
return_VOID;
}
}
table_desc->validation_count--;
if (table_desc->validation_count == 0) {

9
drivers/acpi/acpica/utresrc.c
View File

@ -474,15 +474,6 @@ acpi_ut_walk_aml_resources(struct acpi_walk_state *walk_state,
return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
}
/*
* The end_tag opcode must be followed by a zero byte.
* Although this byte is technically defined to be a checksum,
* in practice, all ASL compilers set this byte to zero.
*/
if (*(aml + 1) != 0) {
return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
}
/* Return the pointer to the end_tag if requested */
if (!user_function) {

14
include/acpi/actbl.h
View File

@ -374,6 +374,20 @@ struct acpi_table_desc {
u16 validation_count;
};
/*
* Maximum value of the validation_count field in struct acpi_table_desc.
* When reached, validation_count cannot be changed any more and the table will
* be permanently regarded as validated.
*
* This is to prevent situations in which unbalanced table get/put operations
* may cause premature table unmapping in the OS to happen.
*
* The maximum validation count can be defined to any value, but should be
* greater than the maximum number of OS early stage mapping slots to avoid
* leaking early stage table mappings to the late stage.
*/
#define ACPI_MAX_TABLE_VALIDATIONS ACPI_UINT16_MAX
/* Masks for Flags field above */
#define ACPI_TABLE_ORIGIN_EXTERNAL_VIRTUAL (0) /* Virtual address, external maintained */