* RV and RW fields must be at the last position in their respective section (per the conditions in the spec). Therefore, the parser now stops iterating over fields as soon as it encounters one of those fields and checks whether the end of the resource has been reached; * Individual fields must have a valid length - the parser needs to check for invalid length values that violate boundary conditions of the resource. * A zero-length field may be the last one in the resource, however, the boundary check is currently too strict to allow that. Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov(a)canonical.com&gt; --- src/util/virpcivpd.c | 28 +++++++++++---- tests/virpcivpdtest.c | 84 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 106 insertions(+), 6 deletions(-) diff --git a/src/util/virpcivpd.c b/src/util/virpcivpd.c index 8856bca459..cd49031fa4 100644 --- a/src/util/virpcivpd.c +++ b/src/util/virpcivpd.c @@ -466,8 +466,12 @@ virPCIVPDParseVPDLargeResourceFields(int vpdFileFd, uint16_t resPos, uint16_t re bool hasChecksum = false; bool hasRW = false; + bool endReached = false; - while (fieldPos + 3 < resPos + resDataLen) { + /* Note the equal sign - fields may have a zero length in which case they will + * just occupy 3 header bytes. In the in case of the RW field this may mean that + * no more space is left in the section. */ + while (fieldPos + 3 <= resPos + resDataLen) { /* Keyword resources consist of keywords (2 ASCII bytes per the spec) and 1-byte length. */ if (virPCIVPDReadVPDBytes(vpdFileFd, buf, 3, fieldPos, csum) != 3) { /* Invalid field encountered which means the resource itself is invalid too. Report @@ -518,6 +522,13 @@ virPCIVPDParseVPDLargeResourceFields(int vpdFileFd, uint16_t resPos, uint16_t re return false; } + if (resPos + resDataLen < fieldPos + fieldDataLen) { + /* In this case the field cannot simply be skipped since the position of the + * next field is determined based on the length of a previous field. */ + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("A field data length violates the resource length boundary.")); + return false; + } if (virPCIVPDReadVPDBytes(vpdFileFd, buf, bytesToRead, fieldPos, csum) != bytesToRead) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("Could not parse a resource field data - VPD has invalid format")); @@ -546,12 +557,13 @@ virPCIVPDParseVPDLargeResourceFields(int vpdFileFd, uint16_t resPos, uint16_t re hasChecksum = true; g_free(g_steal_pointer(&fieldKeyword)); g_free(g_steal_pointer(&fieldValue)); - continue; + break; } else if (fieldFormat == VIR_PCI_VPD_RESOURCE_FIELD_VALUE_FORMAT_RDWR) { /* Skip the read-write space since it is used for indication only. */ hasRW = true; g_free(g_steal_pointer(&fieldKeyword)); g_free(g_steal_pointer(&fieldValue)); + break; } else if (fieldFormat == VIR_PCI_VPD_RESOURCE_FIELD_VALUE_FORMAT_LAST) { /* Skip unknown fields */ g_free(g_steal_pointer(&fieldKeyword)); @@ -579,13 +591,17 @@ virPCIVPDParseVPDLargeResourceFields(int vpdFileFd, uint16_t resPos, uint16_t re g_free(g_steal_pointer(&fieldKeyword)); g_free(g_steal_pointer(&fieldValue)); } - if (readOnly && !hasChecksum) { + + /* May have exited the loop prematurely in case RV or RW were encountered and + * they were not the last fields in the section. */ + endReached = (fieldPos >= resPos + resDataLen); + if (readOnly && !(hasChecksum && endReached)) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("VPD-R does not contain the mandatory RV field")); + _("VPD-R does not contain the mandatory RV field as the last field")); return false; - } else if (!readOnly && !hasRW) { + } else if (!readOnly && !(hasRW && endReached)) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("VPD-W does not contain the mandatory RW field")); + _("VPD-W does not contain the mandatory RW field as the last field")); return false; } diff --git a/tests/virpcivpdtest.c b/tests/virpcivpdtest.c index 2cc9069132..65607c1247 100644 --- a/tests/virpcivpdtest.c +++ b/tests/virpcivpdtest.c @@ -597,6 +597,58 @@ testVirPCIVPDParseFullVPD(const void *opaque G_GNUC_UNUSED) return ret; } +static int +testVirPCIVPDParseZeroLengthRW(const void *opaque G_GNUC_UNUSED) +{ + int fd = -1; + size_t dataLen = 0; + + g_autoptr(virPCIVPDResource) res = NULL; + virPCIVPDResourceCustom *custom = NULL; + + /* The RW field has a zero length which means there is no more RW space left. */ + const uint8_t fullVPDExample[] = { + VPD_STRING_RESOURCE_EXAMPLE_HEADER, VPD_STRING_RESOURCE_EXAMPLE_DATA, + VPD_R_FIELDS_EXAMPLE_HEADER, VPD_R_FIELDS_EXAMPLE_DATA, + PCI_VPD_LARGE_RESOURCE_FLAG | PCI_VPD_READ_WRITE_LARGE_RESOURCE_FLAG, 0x08, 0x00, + 'V', 'Z', 0x02, '4', '2', + 'R', 'W', 0x00, + PCI_VPD_RESOURCE_END_VAL + }; + + dataLen = sizeof(fullVPDExample) / sizeof(uint8_t); + fd = virCreateAnonymousFile(fullVPDExample, dataLen); + res = virPCIVPDParse(fd); + VIR_FORCE_CLOSE(fd); + + if (!res) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "The resource pointer is NULL after parsing which is unexpected"); + return -1; + } + + if (!res->ro) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "Read-only keywords are missing from the VPD resource."); + return -1; + } else if (!res->rw) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "Read-write keywords are missing from the VPD resource."); + return -1; + } + + if (testVirPCIVPDValidateExampleReadOnlyFields(res)) + return -1; + + custom = g_ptr_array_index(res->rw->vendor_specific, 0); + if (custom->idx != 'Z' || STRNEQ_NULLABLE(custom->value, "42")) + return -1; + + custom = NULL; + return 0; +} + + static int testVirPCIVPDParseFullVPDSkipInvalidKeywords(const void *opaque G_GNUC_UNUSED) { @@ -717,6 +769,32 @@ testVirPCIVPDParseFullVPDInvalid(const void *opaque G_GNUC_UNUSED) 'R', 'V', 0x02, 0x8A, 0x00, \ PCI_VPD_RESOURCE_END_VAL +/* The SN field has a length field that goes past the resource boundaries. */ +# define VPD_INVALID_SN_FIELD_LENGTH \ + VPD_STRING_RESOURCE_EXAMPLE_HEADER, \ + 't', 'e', 's', 't', 'n', 'a', 'm', 'e', \ + PCI_VPD_LARGE_RESOURCE_FLAG | PCI_VPD_READ_ONLY_LARGE_RESOURCE_FLAG, 0x0A, 0x00, \ + 'S', 'N', 0x42, 0x04, 0x02, \ + 'R', 'V', 0x02, 0xE8, 0x00, \ + PCI_VPD_RESOURCE_END_VAL + +/* The RV field is not the last one in VPD-R while the checksum is valid. */ +# define VPD_INVALID_RV_NOT_LAST \ + VPD_STRING_RESOURCE_EXAMPLE_HEADER, \ + 't', 'e', 's', 't', 'n', 'a', 'm', 'e', \ + PCI_VPD_LARGE_RESOURCE_FLAG | PCI_VPD_READ_ONLY_LARGE_RESOURCE_FLAG, 0x0A, 0x00, \ + 'R', 'V', 0x02, 0xD1, 0x00, \ + 'S', 'N', 0x02, 0x04, 0x02, \ + PCI_VPD_RESOURCE_END_VAL + +# define VPD_INVALID_RW_NOT_LAST \ + VPD_STRING_RESOURCE_EXAMPLE_HEADER, VPD_STRING_RESOURCE_EXAMPLE_DATA, \ + VPD_R_FIELDS_EXAMPLE_HEADER, VPD_R_FIELDS_EXAMPLE_DATA, \ + PCI_VPD_LARGE_RESOURCE_FLAG | PCI_VPD_READ_WRITE_LARGE_RESOURCE_FLAG, 0x08, 0x00, \ + 'R', 'W', 0x00, \ + 'V', 'Z', 0x02, '4', '2', \ + PCI_VPD_RESOURCE_END_VAL + # define TEST_INVALID_VPD(invalidVPD) \ do { \ g_autoptr(virPCIVPDResource) res = NULL; \ @@ -741,6 +819,9 @@ testVirPCIVPDParseFullVPDInvalid(const void *opaque G_GNUC_UNUSED) TEST_INVALID_VPD(VPD_R_UNEXPECTED_RW_IN_VPD_R_KEY); TEST_INVALID_VPD(VPD_R_INVALID_FIELD_VALUE); TEST_INVALID_VPD(VPD_INVALID_STRING_RESOURCE_VALUE); + TEST_INVALID_VPD(VPD_INVALID_SN_FIELD_LENGTH); + TEST_INVALID_VPD(VPD_INVALID_RV_NOT_LAST); + TEST_INVALID_VPD(VPD_INVALID_RW_NOT_LAST); return 0; } @@ -767,6 +848,9 @@ mymain(void) ret = -1; if (virTestRun("Parsing VPD string resources ", testVirPCIVPDParseVPDStringResource, NULL) < 0) ret = -1; + if (virTestRun("Parsing a VPD resource with a zero-length RW ", + testVirPCIVPDParseZeroLengthRW, NULL) < 0) + ret = -1; if (virTestRun("Parsing a VPD resource with an invalid keyword ", testVirPCIVPDParseFullVPDSkipInvalidKeywords, NULL) < 0) ret = -1; -- 2.32.0

While invalid values need to be ignored when presenting VPD data to the user, it would be good to attempt to parse a valid portion of the VPD instead of marking it invalid as a whole. The particular example encountered on real hardware was twofold: * "N/A" strings present in read-only fields. This would not be a useful valid value for a field, not to mention that if the serial number field with the "N/A" value was parsed, it would confuse higher-level software because this isn't a unique serial for a device; * 0xFF bytes present in VPD-W field values. Those bytes are not valid values and were probably used by the vendor as placeholders. Ignoring the whole VPD because of that would be too strict. Signed-off-by: Dmitrii Shcherbakov <dmitrii.shcherbakov(a)canonical.com&gt; --- src/util/virpcivpd.c | 9 ++-- tests/virpcivpdtest.c | 105 ++++++++++++++++++++++++++++++++++++++---- 2 files changed, 102 insertions(+), 12 deletions(-) diff --git a/src/util/virpcivpd.c b/src/util/virpcivpd.c index cd49031fa4..8c2b17c3a6 100644 --- a/src/util/virpcivpd.c +++ b/src/util/virpcivpd.c @@ -544,9 +544,12 @@ virPCIVPDParseVPDLargeResourceFields(int vpdFileFd, uint16_t resPos, uint16_t re */ fieldValue = g_strstrip(g_strndup((char *)buf, fieldDataLen)); if (!virPCIVPDResourceIsValidTextValue(fieldValue)) { - virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Field value contains invalid characters")); - return false; + /* Skip fields with invalid values - this is safe assuming field length is + * correctly specified. */ + VIR_DEBUG("A value for field %s contains invalid characters", fieldKeyword); + g_free(g_steal_pointer(&fieldKeyword)); + g_free(g_steal_pointer(&fieldValue)); + continue; } } else if (fieldFormat == VIR_PCI_VPD_RESOURCE_FIELD_VALUE_FORMAT_RESVD) { if (*csum) { diff --git a/tests/virpcivpdtest.c b/tests/virpcivpdtest.c index 00e34cc94a..b56f335fab 100644 --- a/tests/virpcivpdtest.c +++ b/tests/virpcivpdtest.c @@ -692,6 +692,99 @@ testVirPCIVPDParseFullVPDSkipInvalidKeywords(const void *opaque G_GNUC_UNUSED) return 0; } +static int +testVirPCIVPDParseFullVPDSkipInvalidValues(const void *opaque G_GNUC_UNUSED) +{ + int fd = -1; + size_t dataLen = 0; + size_t i = 0; + virPCIVPDResourceCustom *custom = NULL; + + g_autoptr(virPCIVPDResource) res = NULL; + + /* This example is based on real-world hardware which was programmed by the vendor with + * invalid field values in both the RO section and RW section. The RO section contains + * only fields with invalid values and the checksum field with a correct checksum. The + * RW field has a 0 length which means there is no more space in the RW section. */ + const uint8_t fullVPDExample[] = { + 0x82, 0x23, 0x00, 0x48, 0x50, 0x20, 0x45, 0x74, 0x68, 0x65, 0x72, 0x6e, 0x65, 0x74, + 0x20, 0x31, 0x47, 0x62, 0x20, 0x32, 0x2d, 0x70, 0x6f, 0x72, 0x74, 0x20, 0x33, 0x36, + 0x31, 0x69, 0x20, 0x41, 0x64, 0x61, 0x70, 0x74, 0x65, 0x72, 0x90, 0x42, 0x00, 0x50, + 0x4e, 0x03, 0x4e, 0x2f, 0x41, 0x45, 0x43, 0x03, 0x4e, 0x2f, 0x41, 0x53, 0x4e, 0x03, + 0x4e, 0x2f, 0x41, 0x56, 0x30, 0x29, 0x34, 0x57, 0x2f, 0x31, 0x57, 0x20, 0x50, 0x43, + 0x49, 0x65, 0x47, 0x32, 0x78, 0x34, 0x20, 0x32, 0x70, 0x20, 0x31, 0x47, 0x62, 0x45, + 0x20, 0x52, 0x4a, 0x34, 0x35, 0x20, 0x49, 0x6e, 0x74, 0x65, 0x6c, 0x20, 0x69, 0x33, + 0x35, 0x30, 0x20, 0x20, 0x20, 0x52, 0x56, 0x01, 0x63, 0x91, 0x47, 0x00, 0x56, 0x31, + 0x06, 0x35, 0x2e, 0x37, 0x2e, 0x30, 0x36, 0x56, 0x33, 0x06, 0x32, 0x2e, 0x38, 0x2e, + 0x32, 0x30, 0x56, 0x36, 0x06, 0x31, 0x2e, 0x35, 0x2e, 0x33, 0x35, 0x59, 0x41, 0x03, + 0x4e, 0x2f, 0x41, 0x59, 0x42, 0x10, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x59, 0x43, 0x0D, 0xff, 0xff, 0xff, + 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 'R', 'W', 0x00, 0x78, + }; + + dataLen = sizeof(fullVPDExample) / sizeof(uint8_t); + fd = virCreateAnonymousFile(fullVPDExample, dataLen); + res = virPCIVPDParse(fd); + VIR_FORCE_CLOSE(fd); + + if (!res) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "The resource pointer is NULL after parsing which is unexpected."); + return -1; + } + /* In this case none of the RO fields have valid contents, however, they have been checksummed + * correctly. Therefore, the RO portion of the resource is not initialized. The checksum + * includes bytes of the device name besides the VPD-R section. So this example is valid + * and, considering the parser is implemented to be graceful about invalid keywords and + * values, this situation is generally possible. */ + if (res->ro) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "The RO section consisting of only invalid fields got parsed successfully"); + return -1; + } + if (!res->rw) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "Could not successfully parse an RW section with some invalid fields"); + return -1; + } + + if (res->rw->asset_tag) { + /* The asset tag has an invalid value in this case so it should be NULL. */ + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "Successfully parsed an invalid asset tag."); + return -1; + } + if (res->rw->vendor_specific->len != 3) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "The number of parsed vendor fields is not equal to the expected number."); + return -1; + } + if (res->rw->system_specific->len > 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + "Successfully parsed some systems-specific fields while none are valid"); + return -1; + } + for (i = 0; i < res->rw->vendor_specific->len; ++i) { + custom = ((virPCIVPDResourceCustom*)g_ptr_array_index(res->rw->vendor_specific, i)); + if (custom->idx == '1') { + if (STRNEQ(custom->value, "5.7.06")) { + return -1; + } + } else if (custom->idx == '3') { + if (STRNEQ(custom->value, "2.8.20")) { + return -1; + } + } else if (custom->idx == '6') { + if (STRNEQ(custom->value, "1.5.35")) { + return -1; + } + } + } + + return 0; +} + + static int testVirPCIVPDParseFullVPDInvalid(const void *opaque G_GNUC_UNUSED) { @@ -753,14 +846,6 @@ testVirPCIVPDParseFullVPDInvalid(const void *opaque G_GNUC_UNUSED) 'R', 'V', 0x02, 0x81, 0x00, \ PCI_VPD_RESOURCE_END_VAL -# define VPD_R_INVALID_FIELD_VALUE \ - VPD_STRING_RESOURCE_EXAMPLE_HEADER, \ - VPD_STRING_RESOURCE_EXAMPLE_DATA, \ - PCI_VPD_LARGE_RESOURCE_FLAG | PCI_VPD_READ_ONLY_LARGE_RESOURCE_FLAG, 0x0A, 0x00, \ - 'S', 'N', 0x02, 0x04, 0x02, \ - 'R', 'V', 0x02, 0x28, 0x00, \ - PCI_VPD_RESOURCE_END_VAL - # define VPD_INVALID_STRING_RESOURCE_VALUE \ VPD_STRING_RESOURCE_EXAMPLE_HEADER, \ 't', 0x03, 's', 't', 'n', 'a', 'm', 'e', \ @@ -833,7 +918,6 @@ testVirPCIVPDParseFullVPDInvalid(const void *opaque G_GNUC_UNUSED) TEST_INVALID_VPD(VPD_R_INVALID_RV); TEST_INVALID_VPD(VPD_R_INVALID_RV_ZERO_LENGTH); TEST_INVALID_VPD(VPD_R_UNEXPECTED_RW_IN_VPD_R_KEY); - TEST_INVALID_VPD(VPD_R_INVALID_FIELD_VALUE); TEST_INVALID_VPD(VPD_INVALID_STRING_RESOURCE_VALUE); TEST_INVALID_VPD(VPD_INVALID_SN_FIELD_LENGTH); TEST_INVALID_VPD(VPD_INVALID_RV_NOT_LAST); @@ -868,6 +952,9 @@ mymain(void) if (virTestRun("Parsing a VPD resource with a zero-length RW ", testVirPCIVPDParseZeroLengthRW, NULL) < 0) ret = -1; + if (virTestRun("Parsing a VPD resource with an invalid values ", + testVirPCIVPDParseFullVPDSkipInvalidValues, NULL) < 0) + ret = -1; if (virTestRun("Parsing a VPD resource with an invalid keyword ", testVirPCIVPDParseFullVPDSkipInvalidKeywords, NULL) < 0) ret = -1; -- 2.32.0

On Fri, Oct 22, 2021 at 03:45:44PM +0300, Dmitrii Shcherbakov wrote: The higher level software needs to acccept that the BIOS vendor might have included garbage and have a plan to deal with this. Libvirt should apply a policy in this regards as it cann result in libvirt rejecting valid data. For example by rejecting "/" as a character, we fail to report valid data from mymachine. If I allow "/" I get: <capability type='vpd'> <name>HP Ethernet 1Gb 2-port 361i Adapter</name> <fields access='readonly'> <change_level>N/A</change_level> <part_number>N/A</part_number> <serial_number>N/A</serial_number> <vendor_field index='0'>4W/1W PCIeG2x4 2p 1GbE RJ45 Intel i350</vendor_field> </fields> <fields access='readwrite'> <asset_tag>N/A</asset_tag> <vendor_field index='1'>5.7.06</vendor_field> <vendor_field index='3'>2.8.20</vendor_field> <vendor_field index='6'>1.5.35</vendor_field> </fields> </capability> sure the "n/a" is unhelpful, but libvirt is right to include it. I think perhaps rather than allow-listing the characters, we need to just accept any field value that contains printable characters. eg instead of the strspn, I'd suggest we do as "isprint()" check on each character This method itself calls virReportError, so we still get stuff reported at level ERROR in the logs. We need to remove the virReportError call in this method. We should include fieldValue in the log, even if it might have non-printable chars, as it'll be important debugging info. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|