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Fix ProbeForRead. It wasn't ever checking if memory can be accessed. Thanks to big-endian it wasn't breaking MmUserProbeAddress as well. Code is now nearly the same as in ProbeForWrite. It shouldn't break anything. If it does, it's not bug in this code. :)

Browse source 
svn path=/trunk/; revision=51108
This commit is contained in:
Rafal Harabien 2011-03-21 14:43:56 +00:00
parent 96de2d1363
commit ec3c8d2441
1 changed files with 21 additions and 6 deletions
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27
reactos/ntoskrnl/ex/exintrin.c
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@ -103,6 +103,8 @@ ProbeForRead(IN CONST VOID *Address,
IN SIZE_T Length,
IN ULONG Alignment)
{
ULONG_PTR Last, Current = (ULONG_PTR)Address;
CHAR Temp;
PAGED_CODE();
/* Only probe if we have a valid length */
@ -115,18 +117,31 @@ ProbeForRead(IN CONST VOID *Address,
(Alignment == 8) ||
(Alignment == 16));
/* Check for correct alignment */
if (((ULONG_PTR)Address & (Alignment - 1)) != 0)
/* Check the alignment */
if ((Current & (Alignment - 1)) != 0)
{
/* Incorrect alignment */
ExRaiseDatatypeMisalignment();
}
else if (((ULONG_PTR)Address + Length) < (ULONG_PTR)Address ||
((ULONG_PTR)Address + Length) > (ULONG_PTR)MmUserProbeAddress)
/* Get the end address */
Last = Current + Length - 1;
if ((Last < Current) || (Last >= (ULONG_PTR)MmUserProbeAddress))
{
/* Raise an access violation */
ExRaiseAccessViolation();
}
/* Round down to the last page */
Last = PAGE_ROUND_DOWN(Last) + PAGE_SIZE;
do
{
/* Attempt a read */
*(volatile CHAR* const)MmUserProbeAddress = 0;
}
Temp = *(volatile CHAR*)Current;
/* Go to the next address */
Current = PAGE_ROUND_DOWN(Current) + PAGE_SIZE;
} while (Current != Last);
}
}