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[FREELDR] PcMemGetBiosMemoryMap(): Add checks for entry sizes and bare handling of error case. CORE-13332

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Serge Gautherie 2017-10-09 01:40:22 +02:00 committed by Thomas Faber
parent 2ddebe3291
commit 1456310503
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2 changed files with 28 additions and 0 deletions
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23
boot/freeldr/freeldr/arch/i386/pcmem.c
View file

@ -293,6 +293,29 @@ PcMemGetBiosMemoryMap(PFREELDR_MEMORY_DESCRIPTOR MemoryMap, ULONG MaxMemoryMapSi
goto nextRange;
}
/* Extra safety: unexpected entry length.
* All in-between values are valid too, as x86 is little-indian
* and only lower byte is used per ACPI 6.2-A.
*/
if (Regs.x.ecx < RTL_SIZEOF_THROUGH_FIELD(BIOS_MEMORY_MAP, Type) ||
Regs.x.ecx > sizeof(BIOS_MEMORY_MAP))
{
ERR("Int 15h AX=E820h returned an invalid entry length! (would-be-PcBiosMapCount = %lu, Entry length = (%Iu <=) %lu (<= %Iu))\n\n",
PcBiosMapCount, RTL_SIZEOF_THROUGH_FIELD(BIOS_MEMORY_MAP, Type), Regs.x.ecx, sizeof(BIOS_MEMORY_MAP));
/* Warn user, unless wrong case is "first and not too big entry", which is otherwise harmless. */
if (PcBiosMapCount > 0 || Regs.x.ecx > sizeof(BIOS_MEMORY_MAP))
{
ASSERTMSG("Int 15h AX=E820h returned an invalid entry length!", FALSE);
}
/* We keep previous entries (if any), but do not dare trying next entries.
* We assume these entries are good to use as is. If they are not, we are in trouble...
* (And don't ask what happens if BIOS actually overflowed our entry buffer...)
*
* FIXME: Safer = revert previous entries, Safest = blacklist this BIOS.
*/
break;
}
/* Copy data to global buffer */
RtlCopyMemory(&PcBiosMemoryMap[PcBiosMapCount], (PVOID)BIOSCALLBUFFER, Regs.x.ecx);

5
boot/freeldr/freeldr/include/arch/pc/pcbios.h
View file

@ -19,6 +19,11 @@ typedef struct
ULONG Reserved;
} BIOS_MEMORY_MAP, *PBIOS_MEMORY_MAP;
/* Int 15h AX=E820h Entry minimal size. */
C_ASSERT(FIELD_OFFSET(BIOS_MEMORY_MAP, Reserved) == 20);
/* Int 15h AX=E820h Entry maximal size. */
C_ASSERT(sizeof(BIOS_MEMORY_MAP) == 24);
/* FIXME: Should be moved to NDK, and respective ACPI header files */
typedef struct _ACPI_BIOS_DATA
{