From 8cdb99af45365727ac17f45239a9b8c1d5155c6d Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Mon, 27 Dec 2021 14:31:17 -0500 Subject: [PATCH] acpi: fix QEMU crash when started with SLIC table MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit if QEMU is started with used provided SLIC table blob, -acpitable sig=SLIC,oem_id='CRASH ',oem_table_id="ME",oem_rev=00002210,asl_compiler_id="",asl_compiler_rev=00000000,data=/dev/null it will assert with: hw/acpi/aml-build.c:61:build_append_padded_str: assertion failed: (len <= maxlen) and following backtrace: ... build_append_padded_str (array=0x555556afe320, str=0x555556afdb2e "CRASH ME", maxlen=0x6, pad=0x20) at hw/acpi/aml-build.c:61 acpi_table_begin (desc=0x7fffffffd1b0, array=0x555556afe320) at hw/acpi/aml-build.c:1727 build_fadt (tbl=0x555556afe320, linker=0x555557ca3830, f=0x7fffffffd318, oem_id=0x555556afdb2e "CRASH ME", oem_table_id=0x555556afdb34 "ME") at hw/acpi/aml-build.c:2064 ... which happens due to acpi_table_begin() expecting NULL terminated oem_id and oem_table_id strings, which is normally the case, but in case of user provided SLIC table, oem_id points to table's blob directly and as result oem_id became longer than expected. Fix issue by handling oem_id consistently and make acpi_get_slic_oem() return NULL terminated strings. PS: After [1] refactoring, oem_id semantics became inconsistent, where NULL terminated string was coming from machine and old way pointer into byte array coming from -acpitable option. That used to work since build_header() wasn't expecting NULL terminated string and blindly copied the 1st 6 bytes only. However commit [2] broke that by replacing build_header() with acpi_table_begin(), which was expecting NULL terminated string and was checking oem_id size. 1) 602b45820 ("acpi: Permit OEM ID and OEM table ID fields to be changed") 2) Fixes: 4b56e1e4eb08 ("acpi: build_fadt: use acpi_table_begin()/acpi_table_end() instead of build_header()") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/786 Signed-off-by: Igor Mammedov Message-Id: <20211227193120.1084176-2-imammedo@redhat.com> Reviewed-by: Philippe Mathieu-Daudé Tested-by: Denis Lisov Tested-by: Alexander Tsoy Cc: qemu-stable@nongnu.org Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/acpi/core.c | 4 ++-- hw/i386/acpi-build.c | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/hw/acpi/core.c b/hw/acpi/core.c index 1e004d0078..3e811bf03c 100644 --- a/hw/acpi/core.c +++ b/hw/acpi/core.c @@ -345,8 +345,8 @@ int acpi_get_slic_oem(AcpiSlicOem *oem) struct acpi_table_header *hdr = (void *)(u - sizeof(hdr->_length)); if (memcmp(hdr->sig, "SLIC", 4) == 0) { - oem->id = hdr->oem_id; - oem->table_id = hdr->oem_table_id; + oem->id = g_strndup(hdr->oem_id, 6); + oem->table_id = g_strndup(hdr->oem_table_id, 8); return 0; } } diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index 8383b83ee3..0234fe7588 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -2723,6 +2723,8 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine) /* Cleanup memory that's no longer used. */ g_array_free(table_offsets, true); + g_free(slic_oem.id); + g_free(slic_oem.table_id); } static void acpi_ram_update(MemoryRegion *mr, GArray *data) -- 2.35.1