From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47625) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuKSB-0002cE-B6 for qemu-devel@nongnu.org; Mon, 18 May 2015 08:47:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YuKS8-00028M-4n for qemu-devel@nongnu.org; Mon, 18 May 2015 08:47:31 -0400 Received: from relay-04.andrew.cmu.edu ([128.2.105.169]:59621 helo=relay.andrew.cmu.edu) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuKS7-00027v-Vt for qemu-devel@nongnu.org; Mon, 18 May 2015 08:47:28 -0400 From: "Gabriel L. Somlo" Date: Mon, 18 May 2015 08:47:24 -0400 Message-Id: <1431953244-29304-1-git-send-email-somlo@cmu.edu> Subject: [Qemu-devel] [PATCH v3] bios-tables-test: handle false-positive smbios signature matches List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: mst@redhat.com, brogers@suse.com, gsomlo@gmail.com, kevin@koconnor.net, kraxel@redhat.com It has been reported that sometimes the .rodata section of SeaBIOS, containing the constant string against which the SMBIOS signature ends up being compared, also falls within the guest f-segment. In that case, the test obviously fails, unless we continue searching for the *real* SMBIOS entry point. Rather than stopping at the first match for the SMBIOS signature ("_SM_") in the f-segment (0xF0000-0xFFFFF), continue scanning until either a valid entry point table is found, or the f-segment has been exhausted. Reported-by: Bruce Rogers Signed-off-by: Gabriel Somlo Tested-by: Bruce Rogers --- - Added motivation for patch in commit log, as requested by mst (whom I forgot to cc on v2 -- D'OH!!! ) :) - Fixed s/withing/within/ as pointed out by eblake Thanks, Gabriel tests/bios-tables-test.c | 76 ++++++++++++++++++++++++++++-------------------- 1 file changed, 44 insertions(+), 32 deletions(-) diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c index 7e85dc4..0de1742 100644 --- a/tests/bios-tables-test.c +++ b/tests/bios-tables-test.c @@ -599,35 +599,15 @@ static void test_acpi_asl(test_data *data) free_test_data(&exp_data); } -static void test_smbios_ep_address(test_data *data) -{ - uint32_t off; - - /* find smbios entry point structure */ - for (off = 0xf0000; off < 0x100000; off += 0x10) { - uint8_t sig[] = "_SM_"; - int i; - - for (i = 0; i < sizeof sig - 1; ++i) { - sig[i] = readb(off + i); - } - - if (!memcmp(sig, "_SM_", sizeof sig)) { - break; - } - } - - g_assert_cmphex(off, <, 0x100000); - data->smbios_ep_addr = off; -} - -static void test_smbios_ep_table(test_data *data) +static bool smbios_ep_table_ok(test_data *data) { struct smbios_entry_point *ep_table = &data->smbios_ep_table; uint32_t addr = data->smbios_ep_addr; ACPI_READ_ARRAY(ep_table->anchor_string, addr); - g_assert(!memcmp(ep_table->anchor_string, "_SM_", 4)); + if (memcmp(ep_table->anchor_string, "_SM_", 4)) { + return false; + } ACPI_READ_FIELD(ep_table->checksum, addr); ACPI_READ_FIELD(ep_table->length, addr); ACPI_READ_FIELD(ep_table->smbios_major_version, addr); @@ -636,17 +616,50 @@ static void test_smbios_ep_table(test_data *data) ACPI_READ_FIELD(ep_table->entry_point_revision, addr); ACPI_READ_ARRAY(ep_table->formatted_area, addr); ACPI_READ_ARRAY(ep_table->intermediate_anchor_string, addr); - g_assert(!memcmp(ep_table->intermediate_anchor_string, "_DMI_", 5)); + if (memcmp(ep_table->intermediate_anchor_string, "_DMI_", 5)) { + return false; + } ACPI_READ_FIELD(ep_table->intermediate_checksum, addr); ACPI_READ_FIELD(ep_table->structure_table_length, addr); - g_assert_cmpuint(ep_table->structure_table_length, >, 0); + if (ep_table->structure_table_length == 0) { + return false; + } ACPI_READ_FIELD(ep_table->structure_table_address, addr); ACPI_READ_FIELD(ep_table->number_of_structures, addr); - g_assert_cmpuint(ep_table->number_of_structures, >, 0); + if (ep_table->number_of_structures == 0) { + return false; + } ACPI_READ_FIELD(ep_table->smbios_bcd_revision, addr); - g_assert(!acpi_checksum((uint8_t *)ep_table, sizeof *ep_table)); - g_assert(!acpi_checksum((uint8_t *)ep_table + 0x10, - sizeof *ep_table - 0x10)); + if (acpi_checksum((uint8_t *)ep_table, sizeof *ep_table) || + acpi_checksum((uint8_t *)ep_table + 0x10, sizeof *ep_table - 0x10)) { + return false; + } + return true; +} + +static void test_smbios_entry_point(test_data *data) +{ + uint32_t off; + + /* find smbios entry point structure */ + for (off = 0xf0000; off < 0x100000; off += 0x10) { + uint8_t sig[] = "_SM_"; + int i; + + for (i = 0; i < sizeof sig - 1; ++i) { + sig[i] = readb(off + i); + } + + if (!memcmp(sig, "_SM_", sizeof sig)) { + /* signature match, but is this a valid entry point? */ + data->smbios_ep_addr = off; + if (smbios_ep_table_ok(data)) { + break; + } + } + } + + g_assert_cmphex(off, <, 0x100000); } static inline bool smbios_single_instance(uint8_t type) @@ -767,8 +780,7 @@ static void test_acpi_one(const char *params, test_data *data) } } - test_smbios_ep_address(data); - test_smbios_ep_table(data); + test_smbios_entry_point(data); test_smbios_structs(data); qtest_quit(global_qtest); -- 2.1.0