s390/sclp: read sccb from mem based on provided length
The header contained within the SCCB passed to the SCLP service call contains the actual length of the SCCB. Instead of allocating a static 4K size for the work sccb, let's allow for a variable size determined by the value in the header. The proper checks are already in place to ensure the SCCB length is sufficent to store a full response and that the length does not cross any explicitly-set boundaries. Signed-off-by: Collin Walling <walling@linux.ibm.com> Reviewed-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Message-Id: <20200915194416.107460-4-walling@linux.ibm.com> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
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@ -213,7 +213,7 @@ static uint16_t handle_sccb_read_events(SCLPEventFacility *ef, SCCB *sccb,
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event_buf = &red->ebh;
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event_buf->length = 0;
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slen = sizeof(sccb->data);
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slen = sccb_data_len(sccb);
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rc = SCLP_RC_NO_EVENT_BUFFERS_STORED;
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@ -231,25 +231,29 @@ int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb,
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{
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SCLPDevice *sclp = get_sclp_device();
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SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp);
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SCCB work_sccb;
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hwaddr sccb_len = sizeof(SCCB);
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SCCBHeader header;
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g_autofree SCCB *work_sccb = NULL;
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s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, sccb_len);
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s390_cpu_pv_mem_read(env_archcpu(env), 0, &header, sizeof(SCCBHeader));
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work_sccb = g_malloc0(be16_to_cpu(header.length));
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s390_cpu_pv_mem_read(env_archcpu(env), 0, work_sccb,
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be16_to_cpu(header.length));
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if (!sclp_command_code_valid(code)) {
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work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
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work_sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
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goto out_write;
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}
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if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb.h.length))) {
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work_sccb.h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
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if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb->h.length))) {
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work_sccb->h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
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goto out_write;
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}
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sclp_c->execute(sclp, &work_sccb, code);
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sclp_c->execute(sclp, work_sccb, code);
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out_write:
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s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb,
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be16_to_cpu(work_sccb.h.length));
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s390_cpu_pv_mem_write(env_archcpu(env), 0, work_sccb,
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be16_to_cpu(work_sccb->h.length));
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sclp_c->service_interrupt(sclp, SCLP_PV_DUMMY_ADDR);
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return 0;
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}
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@ -258,9 +262,8 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
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{
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SCLPDevice *sclp = get_sclp_device();
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SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp);
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SCCB work_sccb;
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hwaddr sccb_len = sizeof(SCCB);
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SCCBHeader header;
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g_autofree SCCB *work_sccb = NULL;
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/* first some basic checks on program checks */
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if (env->psw.mask & PSW_MASK_PSTATE) {
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@ -274,32 +277,36 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
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return -PGM_SPECIFICATION;
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}
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/* the header contains the actual length of the sccb */
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cpu_physical_memory_read(sccb, &header, sizeof(SCCBHeader));
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/* Valid sccb sizes */
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if (be16_to_cpu(header.length) < sizeof(SCCBHeader)) {
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return -PGM_SPECIFICATION;
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}
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/*
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* we want to work on a private copy of the sccb, to prevent guests
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* from playing dirty tricks by modifying the memory content after
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* the host has checked the values
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*/
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cpu_physical_memory_read(sccb, &work_sccb, sccb_len);
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/* Valid sccb sizes */
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if (be16_to_cpu(work_sccb.h.length) < sizeof(SCCBHeader)) {
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return -PGM_SPECIFICATION;
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}
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work_sccb = g_malloc0(be16_to_cpu(header.length));
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cpu_physical_memory_read(sccb, work_sccb, be16_to_cpu(header.length));
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if (!sclp_command_code_valid(code)) {
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work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
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work_sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
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goto out_write;
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}
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if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb.h.length))) {
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work_sccb.h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
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if (!sccb_verify_boundary(sccb, be16_to_cpu(work_sccb->h.length))) {
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work_sccb->h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
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goto out_write;
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}
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sclp_c->execute(sclp, &work_sccb, code);
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sclp_c->execute(sclp, work_sccb, code);
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out_write:
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cpu_physical_memory_write(sccb, &work_sccb,
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be16_to_cpu(work_sccb.h.length));
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cpu_physical_memory_write(sccb, work_sccb,
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be16_to_cpu(work_sccb->h.length));
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sclp_c->service_interrupt(sclp, sccb);
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@ -178,7 +178,7 @@ typedef struct IoaCfgSccb {
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typedef struct SCCB {
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SCCBHeader h;
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char data[SCCB_DATA_LEN];
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char data[];
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} QEMU_PACKED SCCB;
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#define TYPE_SCLP "sclp"
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