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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=148.163.156.1; envelope-from=rathc@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=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 @ibm.com) X-ZM-MESSAGEID: 1787133618065158500 Content-Type: text/plain; charset="utf-8" cdb_offset and local_desc values are dependent on the guest. If the value is large enough, it can lead to an out-of-bounds read in vscsi_fetch_desc(). Add an 'avail' constant in vscsi_preprocess_desc() representing the number = of bytes available in srp_cmd.add_data[] and use it to prevent out-of-bound re= ads. Make all callers of vscsi_preprocess_desc() check its return value and handle failure accordingly. Closes: https://gitlab.com/qemu-project/qemu/-/work_items/4162 Signed-off-by: Chinmay Rath Reported-by: Lazymio --- hw/scsi/spapr_vscsi.c | 43 ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-) diff --git a/hw/scsi/spapr_vscsi.c b/hw/scsi/spapr_vscsi.c index b4c8f94d22..9fef224727 100644 --- a/hw/scsi/spapr_vscsi.c +++ b/hw/scsi/spapr_vscsi.c @@ -484,6 +484,8 @@ static int data_out_desc_size(struct srp_cmd *cmd) static int vscsi_preprocess_desc(vscsi_req *req) { struct srp_cmd *cmd =3D &req_iu(req)->srp.cmd; + /* bytes available for descriptors behind srp_cmd.add_data */ + const unsigned avail =3D SRP_MAX_IU_LEN - offsetof(struct srp_cmd, add= _data); =20 req->cdb_offset =3D cmd->add_cdb_len & ~3; =20 @@ -498,16 +500,35 @@ static int vscsi_preprocess_desc(vscsi_req *req) case SRP_NO_DATA_DESC: break; case SRP_DATA_DESC_DIRECT: + if (req->cdb_offset + sizeof(struct srp_direct_buf) > avail) { + fprintf(stderr, + "vscsi_preprocess_desc: direct desc out of bounds\n"); + return -1; + } req->total_desc =3D req->local_desc =3D 1; break; case SRP_DATA_DESC_INDIRECT: { - struct srp_indirect_buf *ind_tmp =3D (struct srp_indirect_buf *) - (cmd->add_data + req->cdb_offset); + struct srp_indirect_buf *ind_tmp; + + if (req->cdb_offset + sizeof(struct srp_indirect_buf) > avail) { + fprintf(stderr, + "vscsi_preprocess_desc: indirect desc out of bounds\n"= ); + return -1; + } + ind_tmp =3D (struct srp_indirect_buf *)(cmd->add_data + req->cdb_o= ffset); =20 req->total_desc =3D be32_to_cpu(ind_tmp->table_desc.len) / sizeof(struct srp_direct_buf); req->local_desc =3D req->writing ? cmd->data_out_desc_cnt : cmd->data_in_desc_cnt; + + /* desc_list[] entries must also fit inside the IU buffer */ + if (req->local_desc * sizeof(struct srp_direct_buf) > + avail - req->cdb_offset - sizeof(struct srp_indirect_buf)) { + fprintf(stderr, + "vscsi_preprocess_desc: local_desc out of bounds\n"); + return -1; + } break; } default: @@ -725,7 +746,11 @@ static void vscsi_inquiry_no_target(VSCSIState *s, vsc= si_req *req) memcpy(&resp_data[8], "QEMU ", 8); =20 req->writing =3D 0; - vscsi_preprocess_desc(req); + if (vscsi_preprocess_desc(req) < 0) { + vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0); + vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0); + return; + } rc =3D vscsi_srp_transfer_data(s, req, 0, resp_data, len); if (rc < 0) { vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0); @@ -775,7 +800,12 @@ static void vscsi_report_luns(VSCSIState *s, vscsi_req= *req) i +=3D 8; } =20 - vscsi_preprocess_desc(req); + if (vscsi_preprocess_desc(req) < 0) { + g_free(resp_data); + vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0); + vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0); + return; + } rc =3D vscsi_srp_transfer_data(s, req, 0, resp_data, len); g_free(resp_data); if (rc < 0) { @@ -823,7 +853,10 @@ static int vscsi_queue_cmd(VSCSIState *s, vscsi_req *r= eq) req->writing =3D (n < 1); =20 /* Preprocess RDMA descriptors */ - vscsi_preprocess_desc(req); + if (vscsi_preprocess_desc(req) < 0) { + scsi_req_cancel(req->sreq); + return 1; + } =20 /* Get transfer direction and initiate transfer */ if (n > 0) { --=20 2.55.0