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hw/scsi/megasas: Fix possible out-of-bounds array access in tracepoints 

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 <thuth@redhat.com>
Message-Id: <20200615072629.32321-1-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
master
Thomas Huth 2020-06-15 09:26:29 +02:00 committed by Paolo Bonzini
parent 5f509751f7
commit ee760ac80a
1 changed files with 23 additions and 13 deletions
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36
hw/scsi/megasas.c
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@ -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++;