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| author | Ahmed Salem <x0rw3ll@gmail.com> | 2025-04-25 21:30:27 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-05-12 15:38:42 +0200 |
| commit | 64b9dfd0776e9c38d733094859a09f13282ce6f8 (patch) | |
| tree | ed860b4e548480a7d563d2420a6afe907b9d6893 | |
| parent | 5f3cf23f7248d972de12e0bdf42a16eabf5b2b31 (diff) | |
ACPICA: Avoid sequence overread in call to strncmp()
ACPICA commit 8b83a8d88dfec59ea147fad35fc6deea8859c58c
ap_get_table_length() checks if tables are valid by
calling ap_is_valid_header(). The latter then calls
ACPI_VALIDATE_RSDP_SIG(Table->Signature).
ap_is_valid_header() accepts struct acpi_table_header as an argument, so
the signature size is always fixed to 4 bytes.
The problem is when the string comparison is between ACPI-defined table
signature and ACPI_SIG_RSDP. Common ACPI table header specifies the
Signature field to be 4 bytes long[1], with the exception of the RSDP
structure whose signature is 8 bytes long "RSD PTR " (including the
trailing blank character)[2]. Calling strncmp(sig, rsdp_sig, 8) would
then result in a sequence overread[3] as sig would be smaller (4 bytes)
than the specified bound (8 bytes).
As a workaround, pass the bound conditionally based on the size of the
signature being passed.
Link: https://uefi.org/specs/ACPI/6.5_A/05_ACPI_Software_Programming_Model.html#system-description-table-header [1]
Link: https://uefi.org/specs/ACPI/6.5_A/05_ACPI_Software_Programming_Model.html#root-system-description-pointer-rsdp-structure [2]
Link: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wstringop-overread [3]
Link: https://github.com/acpica/acpica/commit/8b83a8d8
Signed-off-by: Ahmed Salem <x0rw3ll@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/2248233.Mh6RI2rZIc@rjwysocki.net
| -rw-r--r-- | include/acpi/actypes.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h index f7b3c4a4b7e7..5b9f9a612548 100644 --- a/include/acpi/actypes.h +++ b/include/acpi/actypes.h @@ -527,7 +527,7 @@ typedef u64 acpi_integer; /* Support for the special RSDP signature (8 characters) */ -#define ACPI_VALIDATE_RSDP_SIG(a) (!strncmp (ACPI_CAST_PTR (char, (a)), ACPI_SIG_RSDP, 8)) +#define ACPI_VALIDATE_RSDP_SIG(a) (!strncmp (ACPI_CAST_PTR (char, (a)), ACPI_SIG_RSDP, (sizeof(a) < 8) ? ACPI_NAMESEG_SIZE : 8)) #define ACPI_MAKE_RSDP_SIG(dest) (memcpy (ACPI_CAST_PTR (char, (dest)), ACPI_SIG_RSDP, 8)) /* Support for OEMx signature (x can be any character) */ |