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

Thomas Huth posted 1 patch 3 years, 11 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20200615072629.32321-1-thuth@redhat.com
Maintainers: Hannes Reinecke <hare@suse.com>, Paolo Bonzini <pbonzini@redhat.com>, Fam Zheng <fam@euphon.net>
hw/scsi/megasas.c | 36 +++++++++++++++++++++++-------------
1 file changed, 23 insertions(+), 13 deletions(-)
[PATCH] hw/scsi/megasas: Fix possible out-of-bounds array access in tracepoints
Posted by Thomas Huth 3 years, 11 months ago 
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>
---
 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++;
-- 
2.18.1
Re: [PATCH] hw/scsi/megasas: Fix possible out-of-bounds array access in tracepoints
Posted by Philippe Mathieu-Daudé 3 years, 11 months ago 
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 <thuth@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 <philmd@redhat.com>
Re: [PATCH] hw/scsi/megasas: Fix possible out-of-bounds array access in tracepoints
Posted by Paolo Bonzini 3 years, 11 months ago 
On 15/06/20 09:26, 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 <thuth@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++;
> 

Queued, thanks.

Paolo

Patchew 2.1-devel-0870f84

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