unify rva checks (#118936)

* unify rva checks

* remove comment

Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: 3 people

src/coreclr/utilcode/pedecoder.cpp

@@ -497,7 +497,6 @@ CHECK PEDecoder::CheckRva(RVA rva, COUNT_T size, int forbiddenFlags, IsNullOK ok
         CHECK(section != NULL);
 
         CHECK(CheckBounds(VAL32(section->VirtualAddress),
-                          // AlignUp((UINT)VAL32(section->Misc.VirtualSize), (UINT)VAL32(FindNTHeaders()->OptionalHeader.SectionAlignment)),
                           (UINT)VAL32(section->Misc.VirtualSize),
                           rva, size));
         if(!IsMapped())
@@ -776,9 +775,17 @@ IMAGE_SECTION_HEADER *PEDecoder::RvaToSection(RVA rva) const
 
     while (section < sectionEnd)
     {
-        if (rva < (VAL32(section->VirtualAddress)
-                   + AlignUp((UINT)VAL32(section->Misc.VirtualSize), (UINT)VAL32(FindNTHeaders()->OptionalHeader.SectionAlignment))))
+        // The RVA should be within a section's virtual address range. 
+        if (rva < (VAL32(section->VirtualAddress) + VAL32(section->Misc.VirtualSize)))
         {
+            if (!IsMapped())
+            {
+                // On flat images (!IsMapped()), the RVA should also be within the section's raw data range.
+                if (rva >= (VAL32(section->VirtualAddress) + VAL32(section->SizeOfRawData)))
+                {
+                    return NULL;
+                }
+            }
             if (rva < VAL32(section->VirtualAddress))
                 RETURN NULL;
             else
@@ -847,7 +854,6 @@ TADDR PEDecoder::GetRvaData(RVA rva, IsNullOK ok /*= NULL_NOT_OK*/) const
         offset = rva;
     else
     {
-        // !!! check for case where rva is in padded portion of segment
         offset = RvaToOffset(rva);
     }