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Fri, 04 Sep 2026 04:43:01 -0700 (PDT) X-Received: by 2002:a05:600d:849b:20b0:499:900c:9c69 with SMTP id 5b1f17b1804b1-49cf825d8c0mr44438075e9.9.1788522180564; Fri, 04 Sep 2026 04:43:00 -0700 (PDT) From: Luigi Leonardi Date: Fri, 04 Sep 2026 13:42:55 +0200 Subject: [PATCH v2 1/2] igvm: validate byte_offset before using it in parameter directives MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260904-fix_offset-v2-1-f5bb4cf6d4b0@redhat.com> References: <20260904-fix_offset-v2-0-f5bb4cf6d4b0@redhat.com> In-Reply-To: <20260904-fix_offset-v2-0-f5bb4cf6d4b0@redhat.com> To: qemu-devel@nongnu.org Cc: Gerd Hoffmann , Stefano Garzarella , Ani Sinha , Luigi Leonardi X-Mailer: b4 0.14.3 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=leonardi@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1788522206090158500 None of the directive handlers that place data at a byte_offset within a parameter area validated that byte_offset actually falls within the parameter area's size. A malformed IGVM file with byte_offset > size would underflow the "size - byte_offset" computation used to determine remaining space, wrapping to a huge value and defeating the size check, then write out of bounds through param_entry->data + byte_offset. Add qigvm_find_param_validate(), which looks up the parameter area, checks byte_offset against its size, and returns the offset-adjusted data pointer and remaining size via output parameters instead of the raw QIgvmParameterData entry. This keeps the byte_offset arithmetic in one place instead of repeating param_entry->data + byte_offset and param_entry->size - byte_offset at every call site. Use it in the vp-count and environment-info handlers, adding an explicit check that the fixed-size write fits in the remaining space. Signed-off-by: Luigi Leonardi --- backends/igvm.c | 68 +++++++++++++++++++++++++++++++++++---= ---- include/system/igvm-internal.h | 6 ++++ 2 files changed, 63 insertions(+), 11 deletions(-) diff --git a/backends/igvm.c b/backends/igvm.c index 7b7bdc72b7..8c07f2ce5e 100644 --- a/backends/igvm.c +++ b/backends/igvm.c @@ -101,6 +101,39 @@ qigvm_find_param_entry(QIgvm *igvm, uint32_t parameter= _area_index, return NULL; } =20 +/* + * Look up a parameter area and check that param->byte_offset falls within + * it, in one step. On success, *data and *size are set to the + * offset-adjusted write location and remaining space within the parameter + * area, so callers never need to touch param->byte_offset themselves. + */ +bool +qigvm_find_param_validate(QIgvm *igvm, uint32_t parameter_area_index, + const IGVM_VHS_PARAMETER *param, + uint8_t **data, uint32_t *size, + Error **errp) +{ + QIgvmParameterData *param_entry; + + assert(data && size); + + param_entry =3D qigvm_find_param_entry(igvm, parameter_area_index, err= p); + if (!param_entry) { + return false; + } + + if (param->byte_offset > param_entry->size) { + error_setg(errp, + "IGVM: byte_offset 0x%x exceeds parameter area size 0x%= x", + param->byte_offset, param_entry->size); + return false; + } + + *data =3D param_entry->data + param->byte_offset; + *size =3D param_entry->size - param->byte_offset; + return true; +} + static int qigvm_directive_page_data(QIgvm *ctx, const uint8_t *header_dat= a, Error **errp); static int qigvm_directive_vp_context(QIgvm *ctx, const uint8_t *header_da= ta, @@ -682,17 +715,24 @@ static int qigvm_directive_vp_count(QIgvm *ctx, const= uint8_t *header_data, Error **errp) { const IGVM_VHS_PARAMETER *param =3D (const IGVM_VHS_PARAMETER *)header= _data; - QIgvmParameterData *param_entry; + uint8_t *data; + uint32_t size; uint32_t *vp_count; CPUState *cpu; =20 - param_entry =3D qigvm_find_param_entry(ctx, - param->parameter_area_index, errp= ); - if (param_entry =3D=3D NULL) { + if (!qigvm_find_param_validate(ctx, param->parameter_area_index, param, + &data, &size, errp)) { + return -1; + } + + if (sizeof(*vp_count) > size) { + error_setg(errp, + "IGVM: vp-count parameter exceeds parameter area " + "defined in IGVM file"); return -1; } =20 - vp_count =3D (uint32_t *)(param_entry->data + param->byte_offset); + vp_count =3D (uint32_t *)data; *vp_count =3D 0; CPU_FOREACH(cpu) { @@ -707,17 +747,23 @@ static int qigvm_directive_environment_info(QIgvm *ct= x, Error **errp) { const IGVM_VHS_PARAMETER *param =3D (const IGVM_VHS_PARAMETER *)header= _data; - QIgvmParameterData *param_entry; + uint8_t *data; + uint32_t size; IgvmEnvironmentInfo *environmental_state; =20 - param_entry =3D qigvm_find_param_entry(ctx, - param->parameter_area_index, errp= ); - if (param_entry =3D=3D NULL) { + if (!qigvm_find_param_validate(ctx, param->parameter_area_index, param, + &data, &size, errp)) { + return -1; + } + + if (sizeof(*environmental_state) > size) { + error_setg(errp, + "IGVM: environment-info parameter exceeds parameter are= a " + "defined in IGVM file"); return -1; } =20 - environmental_state =3D - (IgvmEnvironmentInfo *)(param_entry->data + param->byte_offset); + environmental_state =3D (IgvmEnvironmentInfo *)data; environmental_state->memory_is_shared =3D 1; =20 return 0; diff --git a/include/system/igvm-internal.h b/include/system/igvm-internal.h index 9e9fa1d9af..6526b5055c 100644 --- a/include/system/igvm-internal.h +++ b/include/system/igvm-internal.h @@ -81,4 +81,10 @@ QIgvmParameterData* qigvm_find_param_entry(QIgvm *igvm, uint32_t parameter_area_index, Error **errp); =20 +bool +qigvm_find_param_validate(QIgvm *igvm, uint32_t parameter_area_index, + const IGVM_VHS_PARAMETER *param, + uint8_t **data, uint32_t *size, + Error **errp); 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Fri, 04 Sep 2026 04:43:02 -0700 (PDT) X-Received: by 2002:a05:600c:1551:b0:49c:fa21:e73e with SMTP id 5b1f17b1804b1-49cfa21e935mr35845365e9.20.1788522181747; Fri, 04 Sep 2026 04:43:01 -0700 (PDT) From: Luigi Leonardi Date: Fri, 04 Sep 2026 13:42:56 +0200 Subject: [PATCH v2 2/2] igvm: honor byte_offset when writing memory map, MADT and device tree MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260904-fix_offset-v2-2-f5bb4cf6d4b0@redhat.com> References: <20260904-fix_offset-v2-0-f5bb4cf6d4b0@redhat.com> In-Reply-To: <20260904-fix_offset-v2-0-f5bb4cf6d4b0@redhat.com> To: qemu-devel@nongnu.org Cc: Gerd Hoffmann , Stefano Garzarella , Ani Sinha , Luigi Leonardi X-Mailer: b4 0.14.3 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=leonardi@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1788522199519154100 qigvm_directive_memory_map(), qigvm_directive_madt() and qigvm_directive_device_tree() all wrote their data unconditionally at the start of the parameter area's buffer, ignoring param->byte_offset from the IGVM_VHS_PARAMETER header. This is harmless when a directive's offset happens to be 0, but breaks for IGVM files that pack multiple parameters into a single shared parameter area at different offsets: a later directive would overwrite the data written by an earlier one at the start of the buffer, corrupting it. Switch these handlers to qigvm_find_param_validate(), introduced in the previous patch, and use the offset-adjusted data pointer and remaining size it returns instead of writing at param_entry->data and sizing checks against param_entry->size directly. This both honors byte_offset and validates it against the parameter area size before it is used. Signed-off-by: Luigi Leonardi --- backends/igvm.c | 24 ++++++++++++------------ target/i386/igvm.c | 12 ++++++------ 2 files changed, 18 insertions(+), 18 deletions(-) diff --git a/backends/igvm.c b/backends/igvm.c index 8c07f2ce5e..4d622eac6a 100644 --- a/backends/igvm.c +++ b/backends/igvm.c @@ -638,7 +638,8 @@ static int qigvm_directive_memory_map(QIgvm *ctx, const= uint8_t *header_data, const IGVM_VHS_PARAMETER *param =3D (const IGVM_VHS_PARAMETER *)header= _data; int (*get_mem_map_entry)(int index, ConfidentialGuestMemoryMapEntry *e= ntry, Error **errp) =3D NULL; - QIgvmParameterData *param_entry; + uint8_t *data; + uint32_t size; int max_entry_count; int entry =3D 0; IGVM_VHS_MEMORY_MAP_ENTRY *mm_entry; @@ -659,14 +660,13 @@ static int qigvm_directive_memory_map(QIgvm *ctx, con= st uint8_t *header_data, } =20 /* Find the parameter area that should hold the memory map */ - param_entry =3D qigvm_find_param_entry(ctx, - param->parameter_area_index, errp= ); - if (param_entry =3D=3D NULL) { + if (!qigvm_find_param_validate(ctx, param->parameter_area_index, param, + &data, &size, errp)) { return -1; } =20 - max_entry_count =3D param_entry->size / sizeof(IGVM_VHS_MEMORY_MAP_ENT= RY); - mm_entry =3D (IGVM_VHS_MEMORY_MAP_ENTRY *)param_entry->data; + max_entry_count =3D size / sizeof(IGVM_VHS_MEMORY_MAP_ENTRY); + mm_entry =3D (IGVM_VHS_MEMORY_MAP_ENTRY *)data; =20 retval =3D get_mem_map_entry(entry, &cgmm_entry, errp); while (retval =3D=3D 0) { @@ -860,12 +860,12 @@ static int qigvm_directive_device_tree(QIgvm *ctx, co= nst uint8_t *header_data, { const IGVM_VHS_PARAMETER *param =3D (const IGVM_VHS_PARAMETER *)header= _data; g_autofree void *fdt_packed =3D NULL; - QIgvmParameterData *param_entry; + uint8_t *data; + uint32_t size; uint32_t fdt_size; =20 - param_entry =3D qigvm_find_param_entry(ctx, - param->parameter_area_index, errp= ); - if (param_entry =3D=3D NULL) { + if (!qigvm_find_param_validate(ctx, param->parameter_area_index, param, + &data, &size, errp)) { return -1; } =20 @@ -883,14 +883,14 @@ static int qigvm_directive_device_tree(QIgvm *ctx, co= nst uint8_t *header_data, } =20 fdt_size =3D fdt_totalsize(fdt_packed); - if (fdt_size > param_entry->size) { + if (fdt_size > size) { error_setg(errp, "IGVM: device tree size exceeds parameter area" " defined in IGVM file"); return -1; } =20 - memcpy(param_entry->data, fdt_packed, fdt_size); + memcpy(data, fdt_packed, fdt_size); =20 return 0; } diff --git a/target/i386/igvm.c b/target/i386/igvm.c index ad9bf87761..db365cb80e 100644 --- a/target/i386/igvm.c +++ b/target/i386/igvm.c @@ -187,20 +187,20 @@ void qigvm_x86_bsp_reset(CPUX86State *env) int qigvm_directive_madt(QIgvm *ctx, const uint8_t *header_data, Error **e= rrp) { const IGVM_VHS_PARAMETER *param =3D (const IGVM_VHS_PARAMETER *)header= _data; - QIgvmParameterData *param_entry; + uint8_t *data; + uint32_t size; int result =3D 0; =20 /* Find the parameter area that should hold the MADT data */ - param_entry =3D qigvm_find_param_entry(ctx, - param->parameter_area_index, errp= ); - if (param_entry =3D=3D NULL) { + if (!qigvm_find_param_validate(ctx, param->parameter_area_index, param, + &data, &size, errp)) { return -1; } =20 GArray *madt =3D acpi_build_madt_standalone(ctx->machine_state); =20 - if (madt->len <=3D param_entry->size) { - memcpy(param_entry->data, madt->data, madt->len); + if (madt->len <=3D size) { + memcpy(data, madt->data, madt->len); } else { error_setg( errp, --=20 2.55.0