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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-06-15 10:51:19 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-06-15 10:51:19 +0200 |
commit | 35e60a6b7577218ac7eb7777c8849822a080e127 (patch) | |
tree | a1578093e1e88e17a53ac7b99b0638bd110e04ee | |
parent | Merge tag 'pm-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafa... (diff) | |
parent | Merge branch 'acpica-fixes' (diff) | |
download | linux-35e60a6b7577218ac7eb7777c8849822a080e127.tar.xz linux-35e60a6b7577218ac7eb7777c8849822a080e127.zip |
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"
-rw-r--r-- | drivers/acpi/acpica/tbutils.c | 34 | ||||
-rw-r--r-- | drivers/acpi/acpica/utresrc.c | 9 | ||||
-rw-r--r-- | include/acpi/actbl.h | 14 |
3 files changed, 39 insertions, 18 deletions
diff --git a/drivers/acpi/acpica/tbutils.c b/drivers/acpi/acpica/tbutils.c index 7abe66505739..0d2e98920069 100644 --- a/drivers/acpi/acpica/tbutils.c +++ b/drivers/acpi/acpica/tbutils.c @@ -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) { diff --git a/drivers/acpi/acpica/utresrc.c b/drivers/acpi/acpica/utresrc.c index e0587c85bafd..ff096d9755b9 100644 --- a/drivers/acpi/acpica/utresrc.c +++ b/drivers/acpi/acpica/utresrc.c @@ -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) { diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h index d92543f3bbfd..bdc55c0da19c 100644 --- a/include/acpi/actbl.h +++ b/include/acpi/actbl.h @@ -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 */ |