NetworkPkg/IScsiDxe: fix potential integer overflow in IScsiBinToHex()
Considering IScsiBinToHex():
> if (((*HexLength) - 3) < BinLength * 2) {
> *HexLength = BinLength * 2 + 3;
> }
the following subexpressions are problematic:
(*HexLength) - 3
BinLength * 2
BinLength * 2 + 3
The first one may wrap under zero, the latter two may wrap over
MAX_UINT32.
Rewrite the calculation using SafeIntLib.
While at it, change the type of the "Index" variable from UINTN to UINT32.
The largest "Index"-based value that we calculate is
Index * 2 + 2 (with (Index == BinLength))
Because the patch makes
BinLength * 2 + 3
safe to calculate in UINT32, using UINT32 for
Index * 2 + 2 (with (Index == BinLength))
is safe too. Consistently using UINT32 improves readability.
This patch is best reviewed with "git show -W".
The integer overflows that this patch fixes are theoretical; a subsequent
patch in the series will audit the IScsiBinToHex() call sites, and show
that none of them can fail.
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3356
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210608121259.32451-6-lersek@redhat.com>
diff --git a/NetworkPkg/IScsiDxe/IScsiDxe.inf b/NetworkPkg/IScsiDxe/IScsiDxe.inf
index 543c408..1dde56d 100644
--- a/NetworkPkg/IScsiDxe/IScsiDxe.inf
+++ b/NetworkPkg/IScsiDxe/IScsiDxe.inf
@@ -74,6 +74,7 @@
MemoryAllocationLib
NetLib
PrintLib
+ SafeIntLib
TcpIoLib
UefiBootServicesTableLib
UefiDriverEntryPoint
diff --git a/NetworkPkg/IScsiDxe/IScsiImpl.h b/NetworkPkg/IScsiDxe/IScsiImpl.h
index d895c7f..ac3a257 100644
--- a/NetworkPkg/IScsiDxe/IScsiImpl.h
+++ b/NetworkPkg/IScsiDxe/IScsiImpl.h
@@ -44,6 +44,7 @@
#include <Library/MemoryAllocationLib.h>
#include <Library/NetLib.h>
#include <Library/PrintLib.h>
+#include <Library/SafeIntLib.h>
#include <Library/TcpIoLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiHiiServicesLib.h>
diff --git a/NetworkPkg/IScsiDxe/IScsiMisc.c b/NetworkPkg/IScsiDxe/IScsiMisc.c
index b8fef3f..42988e1 100644
--- a/NetworkPkg/IScsiDxe/IScsiMisc.c
+++ b/NetworkPkg/IScsiDxe/IScsiMisc.c
@@ -316,6 +316,7 @@
@retval EFI_SUCCESS The binary data is converted to the hexadecimal string
and the length of the string is updated.
@retval EFI_BUFFER_TOO_SMALL The string is too small.
+ @retval EFI_BAD_BUFFER_SIZE BinLength is too large for hex encoding.
@retval EFI_INVALID_PARAMETER The IP string is malformatted.
**/
@@ -327,18 +328,28 @@
IN OUT UINT32 *HexLength
)
{
- UINTN Index;
+ UINT32 HexLengthMin;
+ UINT32 HexLengthProvided;
+ UINT32 Index;
if ((HexStr == NULL) || (BinBuffer == NULL) || (BinLength == 0)) {
return EFI_INVALID_PARAMETER;
}
- if (((*HexLength) - 3) < BinLength * 2) {
- *HexLength = BinLength * 2 + 3;
+ //
+ // Safely calculate: HexLengthMin := BinLength * 2 + 3.
+ //
+ if (RETURN_ERROR (SafeUint32Mult (BinLength, 2, &HexLengthMin)) ||
+ RETURN_ERROR (SafeUint32Add (HexLengthMin, 3, &HexLengthMin))) {
+ return EFI_BAD_BUFFER_SIZE;
+ }
+
+ HexLengthProvided = *HexLength;
+ *HexLength = HexLengthMin;
+ if (HexLengthProvided < HexLengthMin) {
return EFI_BUFFER_TOO_SMALL;
}
- *HexLength = BinLength * 2 + 3;
//
// Prefix for Hex String.
//
diff --git a/NetworkPkg/IScsiDxe/IScsiMisc.h b/NetworkPkg/IScsiDxe/IScsiMisc.h
index 46c725a..2314139 100644
--- a/NetworkPkg/IScsiDxe/IScsiMisc.h
+++ b/NetworkPkg/IScsiDxe/IScsiMisc.h
@@ -150,6 +150,7 @@
@retval EFI_SUCCESS The binary data is converted to the hexadecimal string
and the length of the string is updated.
@retval EFI_BUFFER_TOO_SMALL The string is too small.
+ @retval EFI_BAD_BUFFER_SIZE BinLength is too large for hex encoding.
@retval EFI_INVALID_PARAMETER The IP string is malformatted.
**/
