NetworkPkg: UefiPxeBcDxe: SECURITY PATCH CVE-2023-45235 Patch

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=4540

Bug Details:
PixieFail Bug #7
CVE-2023-45235
CVSS 8.3 : CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
CWE-119 Improper Restriction of Operations within the Bounds of
 a Memory Buffer

Buffer overflow when handling Server ID option from a DHCPv6 proxy
Advertise message

Change Overview:

Performs two checks

1. Checks that the length of the duid is accurate
> + //
> + // Check that the minimum and maximum requirements are met
> + //
> + if ((OpLen < PXEBC_MIN_SIZE_OF_DUID) ||
(OpLen > PXEBC_MAX_SIZE_OF_DUID)) {
> +  Status = EFI_INVALID_PARAMETER;
> +  goto ON_ERROR;
> + }

2. Ensures that the amount of data written to the buffer is tracked and
never exceeds that
> + //
> + // Check that the option length is valid.
> + //
> + if ((DiscoverLen + OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN)
 > DiscoverLenNeeded) {
> +     Status = EFI_OUT_OF_RESOURCES;
> +     goto ON_ERROR;
> + }

Additional code clean up and fix for memory leak in case Option was NULL

Cc: Saloni Kasbekar <saloni.kasbekar@intel.com>
Cc: Zachary Clark-williams <zachary.clark-williams@intel.com>

Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com>
Reviewed-by: Saloni Kasbekar <saloni.kasbekar@intel.com>

2 files changed, 78 insertions, 16 deletions

diff --git a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c
index 2b2d372889..7fd1281c11 100644
--- a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c
+++ b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c
@@ -887,6 +887,7 @@ PxeBcRequestBootService (
   EFI_STATUS                       Status;

   EFI_DHCP6_PACKET                 *IndexOffer;

   UINT8                            *Option;

+  UINTN                            DiscoverLenNeeded;

 

   PxeBc      = &Private->PxeBc;

   Request    = Private->Dhcp6Request;

@@ -899,7 +900,8 @@ PxeBcRequestBootService (
     return EFI_DEVICE_ERROR;

   }

 

-  Discover = AllocateZeroPool (sizeof (EFI_PXE_BASE_CODE_DHCPV6_PACKET));

+  DiscoverLenNeeded = sizeof (EFI_PXE_BASE_CODE_DHCPV6_PACKET);

+  Discover          = AllocateZeroPool (DiscoverLenNeeded);

   if (Discover == NULL) {

     return EFI_OUT_OF_RESOURCES;

   }

@@ -924,16 +926,34 @@ PxeBcRequestBootService (
                DHCP6_OPT_SERVER_ID

                );

     if (Option == NULL) {

-      return EFI_NOT_FOUND;

+      Status = EFI_NOT_FOUND;

+      goto ON_ERROR;

     }

 

     //

     // Add Server ID Option.

     //

     OpLen = NTOHS (((EFI_DHCP6_PACKET_OPTION *)Option)->OpLen);

-    CopyMem (DiscoverOpt, Option, OpLen + 4);

-    DiscoverOpt += (OpLen + 4);

-    DiscoverLen += (OpLen + 4);

+

+    //

+    // Check that the minimum and maximum requirements are met

+    //

+    if ((OpLen < PXEBC_MIN_SIZE_OF_DUID) || (OpLen > PXEBC_MAX_SIZE_OF_DUID)) {

+      Status = EFI_INVALID_PARAMETER;

+      goto ON_ERROR;

+    }

+

+    //

+    // Check that the option length is valid.

+    //

+    if ((DiscoverLen + OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN) > DiscoverLenNeeded) {

+      Status = EFI_OUT_OF_RESOURCES;

+      goto ON_ERROR;

+    }

+

+    CopyMem (DiscoverOpt, Option, OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+    DiscoverOpt += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+    DiscoverLen += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

   }

 

   while (RequestLen < Request->Length) {

@@ -945,15 +965,23 @@ PxeBcRequestBootService (
         )

     {

       //

+      // Check that the option length is valid.

+      //

+      if (DiscoverLen + OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN > DiscoverLenNeeded) {

+        Status = EFI_OUT_OF_RESOURCES;

+        goto ON_ERROR;

+      }

+

+      //

       // Copy all the options except IA option and Server ID

       //

-      CopyMem (DiscoverOpt, RequestOpt, OpLen + 4);

-      DiscoverOpt += (OpLen + 4);

-      DiscoverLen += (OpLen + 4);

+      CopyMem (DiscoverOpt, RequestOpt, OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+      DiscoverOpt += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+      DiscoverLen += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

     }

 

-    RequestOpt += (OpLen + 4);

-    RequestLen += (OpLen + 4);

+    RequestOpt += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+    RequestLen += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

   }

 

   //

@@ -2154,6 +2182,7 @@ PxeBcDhcp6Discover (
   UINT16                           OpLen;

   UINT32                           Xid;

   EFI_STATUS                       Status;

+  UINTN                            DiscoverLenNeeded;

 

   PxeBc    = &Private->PxeBc;

   Mode     = PxeBc->Mode;

@@ -2169,7 +2198,8 @@ PxeBcDhcp6Discover (
     return EFI_DEVICE_ERROR;

   }

 

-  Discover = AllocateZeroPool (sizeof (EFI_PXE_BASE_CODE_DHCPV6_PACKET));

+  DiscoverLenNeeded = sizeof (EFI_PXE_BASE_CODE_DHCPV6_PACKET);

+  Discover          = AllocateZeroPool (DiscoverLenNeeded);

   if (Discover == NULL) {

     return EFI_OUT_OF_RESOURCES;

   }

@@ -2185,22 +2215,37 @@ PxeBcDhcp6Discover (
   DiscoverLen             = sizeof (EFI_DHCP6_HEADER);

   RequestLen              = DiscoverLen;

 

+  //

+  // The request packet is generated by the UEFI network stack. In the DHCP4 DORA and DHCP6 SARR sequence,

+  // the first (discover in DHCP4 and solicit in DHCP6) and third (request in both DHCP4 and DHCP6) are

+  // generated by the DHCP client (the UEFI network stack in this case). By the time this function executes,

+  // the DHCP sequence already has been executed once (see UEFI Specification Figures 24.2 and 24.3), with

+  // Private->Dhcp6Request being a cached copy of the DHCP6 request packet that UEFI network stack previously

+  // generated and sent.

+  //

+  // Therefore while this code looks like it could overflow, in practice it's not possible.

+  //

   while (RequestLen < Request->Length) {

     OpCode = NTOHS (((EFI_DHCP6_PACKET_OPTION *)RequestOpt)->OpCode);

     OpLen  = NTOHS (((EFI_DHCP6_PACKET_OPTION *)RequestOpt)->OpLen);

     if ((OpCode != EFI_DHCP6_IA_TYPE_NA) &&

         (OpCode != EFI_DHCP6_IA_TYPE_TA))

     {

+      if (DiscoverLen + OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN > DiscoverLenNeeded) {

+        Status = EFI_OUT_OF_RESOURCES;

+        goto ON_ERROR;

+      }

+

       //

       // Copy all the options except IA option.

       //

-      CopyMem (DiscoverOpt, RequestOpt, OpLen + 4);

-      DiscoverOpt += (OpLen + 4);

-      DiscoverLen += (OpLen + 4);

+      CopyMem (DiscoverOpt, RequestOpt, OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+      DiscoverOpt += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+      DiscoverLen += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

     }

 

-    RequestOpt += (OpLen + 4);

-    RequestLen += (OpLen + 4);

+    RequestOpt += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

+    RequestLen += (OpLen + PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN);

   }

 

   Status = PxeBc->UdpWrite (

diff --git a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h
index c86f6d391b..6357d27fae 100644
--- a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h
+++ b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h
@@ -34,6 +34,23 @@
 #define PXEBC_ADDR_START_DELIMITER        '['

 #define PXEBC_ADDR_END_DELIMITER          ']'

 

+//

+// A DUID consists of a 2-octet type code represented in network byte

+// order, followed by a variable number of octets that make up the

+// actual identifier.  The length of the DUID (not including the type

+// code) is at least 1 octet and at most 128 octets.

+//

+#define PXEBC_MIN_SIZE_OF_DUID  (sizeof(UINT16) + 1)

+#define PXEBC_MAX_SIZE_OF_DUID  (sizeof(UINT16) + 128)

+

+//

+// This define represents the combineds code and length field from

+// https://datatracker.ietf.org/doc/html/rfc3315#section-22.1

+//

+#define PXEBC_COMBINED_SIZE_OF_OPT_CODE_AND_LEN  \

+      (sizeof (((EFI_DHCP6_PACKET_OPTION *)0)->OpCode) + \

+      sizeof (((EFI_DHCP6_PACKET_OPTION *)0)->OpLen))

+

 #define GET_NEXT_DHCP6_OPTION(Opt) \

   (EFI_DHCP6_PACKET_OPTION *) ((UINT8 *) (Opt) + \

   sizeof (EFI_DHCP6_PACKET_OPTION) + (NTOHS ((Opt)->OpLen)) - 1)