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envelope-from=rathc@linux.ibm.com; helo=mx0b-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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 8/19/26 15:28, Chinmay Rath wrote: > 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 reads. > > 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 = &req_iu(req)->srp.cmd; > + /* bytes available for descriptors behind srp_cmd.add_data */ > + const unsigned avail = SRP_MAX_IU_LEN - offsetof(struct srp_cmd, add_data); > > req->cdb_offset = cmd->add_cdb_len & ~3; > > @@ -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 = req->local_desc = 1; > break; > case SRP_DATA_DESC_INDIRECT: { > - struct srp_indirect_buf *ind_tmp = (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 = (struct srp_indirect_buf *)(cmd->add_data + req->cdb_offset); > > req->total_desc = be32_to_cpu(ind_tmp->table_desc.len) / > sizeof(struct srp_direct_buf); > req->local_desc = 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, vscsi_req *req) > memcpy(&resp_data[8], "QEMU ", 8); > > req->writing = 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 = 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 += 8; > } > > - 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 = 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 *req) > req->writing = (n < 1); > > /* Preprocess RDMA descriptors */ > - vscsi_preprocess_desc(req); > + if (vscsi_preprocess_desc(req) < 0) { > + scsi_req_cancel(req->sreq); > + return 1; > + } > > /* Get transfer direction and initiate transfer */ > if (n > 0) {