On 6/15/20 9:26 AM, Thomas Huth wrote: > Some tracepoints in megasas.c use a guest-controlled value as an index > into the mfi_frame_desc[] array. Thus a malicious guest could cause an > out-of-bounds error here. Fortunately, the impact is very low since this > can only happen when the corresponding tracepoints have been enabled > before, but the problem should be fixed anyway with a proper check. > > Buglink: https://bugs.launchpad.net/qemu/+bug/1882065 > Signed-off-by: Thomas Huth <th...@redhat.com> > --- > hw/scsi/megasas.c | 36 +++++++++++++++++++++++------------- > 1 file changed, 23 insertions(+), 13 deletions(-) > > diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c > index af18c88b65..aa930226f8 100644 > --- a/hw/scsi/megasas.c > +++ b/hw/scsi/megasas.c > @@ -54,10 +54,6 @@ > #define MEGASAS_FLAG_USE_QUEUE64 1 > #define MEGASAS_MASK_USE_QUEUE64 (1 << MEGASAS_FLAG_USE_QUEUE64) > > -static const char *mfi_frame_desc[] = { > - "MFI init", "LD Read", "LD Write", "LD SCSI", "PD SCSI", > - "MFI Doorbell", "MFI Abort", "MFI SMP", "MFI Stop"}; > - > typedef struct MegasasCmd { > uint32_t index; > uint16_t flags; > @@ -183,6 +179,20 @@ static void megasas_frame_set_scsi_status(MegasasState > *s, > stb_pci_dma(pci, frame + offsetof(struct mfi_frame_header, scsi_status), > v); > } > > +static inline const char *mfi_frame_desc(unsigned int cmd) > +{ > + static const char *mfi_frame_descs[] = { > + "MFI init", "LD Read", "LD Write", "LD SCSI", "PD SCSI", > + "MFI Doorbell", "MFI Abort", "MFI SMP", "MFI Stop" > + }; > + > + if (cmd < ARRAY_SIZE(mfi_frame_descs)) { > + return mfi_frame_descs[cmd]; > + } > + > + return "Unknown"; > +} > + > /* > * Context is considered opaque, but the HBA firmware is running > * in little endian mode. So convert it to little endian, too. > @@ -1670,25 +1680,25 @@ static int megasas_handle_scsi(MegasasState *s, > MegasasCmd *cmd, > if (is_logical) { > if (target_id >= MFI_MAX_LD || lun_id != 0) { > trace_megasas_scsi_target_not_present( > - mfi_frame_desc[frame_cmd], is_logical, target_id, lun_id); > + mfi_frame_desc(frame_cmd), is_logical, target_id, lun_id); > return MFI_STAT_DEVICE_NOT_FOUND; > } > } > sdev = scsi_device_find(&s->bus, 0, target_id, lun_id); > > cmd->iov_size = le32_to_cpu(cmd->frame->header.data_len); > - trace_megasas_handle_scsi(mfi_frame_desc[frame_cmd], is_logical, > + trace_megasas_handle_scsi(mfi_frame_desc(frame_cmd), is_logical, > target_id, lun_id, sdev, cmd->iov_size); > > if (!sdev || (megasas_is_jbod(s) && is_logical)) { > trace_megasas_scsi_target_not_present( > - mfi_frame_desc[frame_cmd], is_logical, target_id, lun_id); > + mfi_frame_desc(frame_cmd), is_logical, target_id, lun_id); > return MFI_STAT_DEVICE_NOT_FOUND; > } > > if (cdb_len > 16) { > trace_megasas_scsi_invalid_cdb_len( > - mfi_frame_desc[frame_cmd], is_logical, > + mfi_frame_desc(frame_cmd), is_logical, > target_id, lun_id, cdb_len); > megasas_write_sense(cmd, SENSE_CODE(INVALID_OPCODE)); > cmd->frame->header.scsi_status = CHECK_CONDITION; > @@ -1706,7 +1716,7 @@ static int megasas_handle_scsi(MegasasState *s, > MegasasCmd *cmd, > cmd->req = scsi_req_new(sdev, cmd->index, lun_id, cdb, cmd); > if (!cmd->req) { > trace_megasas_scsi_req_alloc_failed( > - mfi_frame_desc[frame_cmd], target_id, lun_id); > + mfi_frame_desc(frame_cmd), target_id, lun_id); > megasas_write_sense(cmd, SENSE_CODE(NO_SENSE)); > cmd->frame->header.scsi_status = BUSY; > s->event_count++; > @@ -1751,17 +1761,17 @@ static int megasas_handle_io(MegasasState *s, > MegasasCmd *cmd, int frame_cmd) > } > > trace_megasas_handle_io(cmd->index, > - mfi_frame_desc[frame_cmd], target_id, lun_id, > + mfi_frame_desc(frame_cmd), target_id, lun_id, > (unsigned long)lba_start, (unsigned > long)lba_count); > if (!sdev) { > trace_megasas_io_target_not_present(cmd->index, > - mfi_frame_desc[frame_cmd], target_id, lun_id); > + mfi_frame_desc(frame_cmd), target_id, lun_id); > return MFI_STAT_DEVICE_NOT_FOUND; > } > > if (cdb_len > 16) { > trace_megasas_scsi_invalid_cdb_len( > - mfi_frame_desc[frame_cmd], 1, target_id, lun_id, cdb_len); > + mfi_frame_desc(frame_cmd), 1, target_id, lun_id, cdb_len); > megasas_write_sense(cmd, SENSE_CODE(INVALID_OPCODE)); > cmd->frame->header.scsi_status = CHECK_CONDITION; > s->event_count++; > @@ -1781,7 +1791,7 @@ static int megasas_handle_io(MegasasState *s, > MegasasCmd *cmd, int frame_cmd) > lun_id, cdb, cmd); > if (!cmd->req) { > trace_megasas_scsi_req_alloc_failed( > - mfi_frame_desc[frame_cmd], target_id, lun_id); > + mfi_frame_desc(frame_cmd), target_id, lun_id); > megasas_write_sense(cmd, SENSE_CODE(NO_SENSE)); > cmd->frame->header.scsi_status = BUSY; > s->event_count++; >
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
