From patchwork Fri Apr 25 19:30:27 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Rafael J. 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Wysocki" To: Linux ACPI Cc: LKML , Bob Moore , Saket Dumbre Subject: [PATCH v1 16/19] ACPICA: Avoid sequence overread in call to strncmp() Date: Fri, 25 Apr 2025 21:30:27 +0200 Message-ID: <2248233.Mh6RI2rZIc@rjwysocki.net> In-Reply-To: <12671029.O9o76ZdvQC@rjwysocki.net> References: <12671029.O9o76ZdvQC@rjwysocki.net> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CLIENT-IP: 217.114.34.19 X-CLIENT-HOSTNAME: 217.114.34.19 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvheefudelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecujffqoffgrffnpdggtffipffknecuuegrihhlohhuthemucduhedtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufffkfgjfhgggfgtsehtufertddttdejnecuhfhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqnecuggftrfgrthhtvghrnhepieefkefgffetfffgleduffffjeeuveegvdefkedtjeefjeffhfdtkeffjeeffeffnecuffhomhgrihhnpehuvghfihdrohhrghdpghhnuhdrohhrghdpghhithhhuhgsrdgtohhmnecukfhppedvudejrdduudegrdefgedrudelnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepvddujedruddugedrfeegrdduledphhgvlhhopehkrhgvrggthhgvrhdrlhhotggrlhhnvghtpdhmrghilhhfrhhomheprhhjfiesrhhjfiihshhotghkihdrnhgvthdpnhgspghrtghpthhtohepgedprhgtphhtthhopehlihhnuhigqdgrtghpihesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehrohgsvghrthdrmhhoohhrvgesihhnthgvlhdrtghomhdprhgtphhtthhopehsrghkvghtrdguuhhmsghrvgesihh X-DCC--Metrics: v370.home.net.pl 1024; Body=4 Fuz1=4 Fuz2=4 From: Ahmed Salem 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 Signed-off-by: Rafael J. Wysocki --- include/acpi/actypes.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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) */