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Skipping update memory attributes when image does not support NX #745

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Skipping update memory attributes when image does not support NX #745

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36 changes: 24 additions & 12 deletions pe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -605,6 +605,7 @@ handle_image (void *data, unsigned int datasize,
int found_entry_point = 0;
UINT8 sha1hash[SHA1_DIGEST_SIZE];
UINT8 sha256hash[SHA256_DIGEST_SIZE];
bool nx_compat = 0;

/*
* The binary header contains relevant context and section pointers
Expand Down Expand Up @@ -697,12 +698,16 @@ handle_image (void *data, unsigned int datasize,
return EFI_OUT_OF_RESOURCES;
}

nx_compat = (context.DllCharacteristics & EFI_IMAGE_DLLCHARACTERISTICS_NX_COMPAT);
buffer = (void *)ALIGN_VALUE((unsigned long)*alloc_address, *alloc_alignment);
dprint(L"Loading 0x%llx bytes at 0x%llx\n",
(unsigned long long)context.ImageSize,
(unsigned long long)(uintptr_t)buffer);
update_mem_attrs((uintptr_t)buffer, alloc_size, MEM_ATTR_R|MEM_ATTR_W,
MEM_ATTR_X);
if (nx_compat)
update_mem_attrs((uintptr_t)buffer, alloc_size,
MEM_ATTR_R|MEM_ATTR_W, MEM_ATTR_X);
else
perror(L"Image does not support NX\n");

CopyMem(buffer, data, context.SizeOfHeaders);

Expand Down Expand Up @@ -872,7 +877,6 @@ handle_image (void *data, unsigned int datasize,
uint64_t clear_attrs = MEM_ATTR_W|MEM_ATTR_X;
uintptr_t addr;
uint64_t raw_length;
uint64_t length;

/*
* Skip discardable sections with zero size
Expand All @@ -899,17 +903,25 @@ handle_image (void *data, unsigned int datasize,
// granularity, but the section length (unlike the section
// address) is not required to be aligned.
raw_length = (uintptr_t)end - (uintptr_t)base + 1;
length = ALIGN_VALUE(raw_length, PAGE_SIZE);

if (Section->Characteristics & EFI_IMAGE_SCN_MEM_WRITE) {
set_attrs |= MEM_ATTR_W;
clear_attrs &= ~MEM_ATTR_W;
}
if (Section->Characteristics & EFI_IMAGE_SCN_MEM_EXECUTE) {
set_attrs |= MEM_ATTR_X;
clear_attrs &= ~MEM_ATTR_X;
/*
* Now set the page permissions appropriately if we're
* enforcing NX compat.
*/
if (!nx_compat) {
uint64_t length;
length = ALIGN_VALUE(raw_length, PAGE_SIZE);

if (Section->Characteristics & EFI_IMAGE_SCN_MEM_WRITE) {
set_attrs |= MEM_ATTR_W;
clear_attrs &= ~MEM_ATTR_W;
}
if (Section->Characteristics & EFI_IMAGE_SCN_MEM_EXECUTE) {
set_attrs |= MEM_ATTR_X;
clear_attrs &= ~MEM_ATTR_X;
}
update_mem_attrs(addr, length, set_attrs, clear_attrs);
}
update_mem_attrs(addr, length, set_attrs, clear_attrs);

/*
* We only cache CODE and INITIALIZED data sections that
Expand Down