From: Doug Flick <dougfl...@microsoft.com>
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.kasbe...@intel.com>
Cc: Zachary Clark-williams <zachary.clark-willi...@intel.com>
Signed-off-by: Doug Flick [MSFT] <doug.e...@gmail.com>
---
NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h | 17 ++++++
NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c | 77 ++++++++++++++++++++++------
2 files changed, 78 insertions(+), 16 deletions(-)
diff --git a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h
b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.h
index c86f6d391b80..6357d27faefd 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)
diff --git a/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c
b/NetworkPkg/UefiPxeBcDxe/PxeBcDhcp6.c
index 2b2d372889a3..7fd1281c1184 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) {
@@ -944,16 +964,24 @@ PxeBcRequestBootService (
(OpCode != DHCP6_OPT_SERVER_ID)
)
{
+ //
+ // 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 (
--
2.43.0
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