SymbX/systemd
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

boot: Fix UKI boot for kernels with non-zero ImageBase (#40429)

Browse Source 
The current code incorrectly subtracts ImageBase from section
VirtualAddress values when loading sections into memory. This is based
on a misunderstanding of the PE specification.

VirtualAddress in section headers is the address of the first byte of
the section relative to the image base when the section is loaded into
memory. In other words, VirtualAddress is already an RVA measured from
the image base, it is definitely NOT an absolute address that needs to
be adjusted.

So when loading a PE image into a newly allocated buffer, sections
should be copied to buffer + VirtualAddress, regardless of what
ImageBase says. The ImageBase field merely indicates the *preferred*
load address, it does not affect how section RVAs are interpreted.

This happens to not cause issues when ImageBase was 0 (since
VirtualAddress - 0 = VirtualAddress), which is why this bug went
undetected on modern kernels. However, it fails with kernels that have
non-zero ImageBase values.

So let's remove the nonsensical VirtualAddress < ImageBase check, and
remove the ImageBase subtractions from section loading offsets. This
lets all kernel UKIs work properly again.

Fixes: #40342
This commit is contained in:
Yu Watanabe
2026-02-18 03:27:41 +09:00
committed by GitHub
parent e38fac0cc5 353701b07e
commit 78a61335e3
4 changed files with 7 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/boot/boot.c
+1 -1
View File
@@ -2785,7 +2785,7 @@ static EFI_STATUS call_image_start(
uint32_t compat_address;
err = pe_kernel_info(loaded_image->ImageBase, /* ret_entry_point= */ NULL, &compat_address,
/* ret_image_base= */ NULL, /* ret_size_in_memory= */ NULL);
/* ret_size_in_memory= */ NULL);
if (err != EFI_SUCCESS) {
if (err != EFI_UNSUPPORTED)
return log_error_status(err, "Error finding kernel compat entry address: %m");
src/boot/linux.c
+4 -6
View File
@@ -161,14 +161,13 @@ EFI_STATUS linux_exec(
size_t kernel_size_in_memory = 0;
uint32_t compat_entry_point, entry_point;
uint64_t image_base;
EFI_STATUS err;
assert(parent_image);
assert(iovec_is_set(kernel));
assert(iovec_is_valid(initrd));
err = pe_kernel_info(kernel->iov_base, &entry_point, &compat_entry_point, &image_base, &kernel_size_in_memory);
err = pe_kernel_info(kernel->iov_base, &entry_point, &compat_entry_point, &kernel_size_in_memory);
#if defined(__i386__) || defined(__x86_64__)
if (err == EFI_UNSUPPORTED)
/* Kernel is too old to support LINUX_INITRD_MEDIA_GUID, try the deprecated EFI handover
@@ -276,10 +275,9 @@ EFI_STATUS linux_exec(
if (h->SizeOfRawData == 0)
continue;
if ((h->VirtualAddress < image_base)
|| (h->VirtualAddress - image_base + h->SizeOfRawData > kernel_size_in_memory))
if (h->VirtualAddress + h->SizeOfRawData > kernel_size_in_memory)
return log_error_status(EFI_LOAD_ERROR, "Section would write outside of memory");
memcpy(loaded_kernel + h->VirtualAddress - image_base,
memcpy(loaded_kernel + h->VirtualAddress,
(const uint8_t*)kernel->iov_base + h->PointerToRawData,
h->SizeOfRawData);
memzero(loaded_kernel + h->VirtualAddress + h->SizeOfRawData,
@@ -288,7 +286,7 @@ EFI_STATUS linux_exec(
/* Not a code section? Nothing to do, leave as-is. */
if (memory_proto && (h->Characteristics & (PE_CODE|PE_EXECUTE))) {
nx_sections = xrealloc(nx_sections, n_nx_sections * sizeof(struct iovec), (n_nx_sections + 1) * sizeof(struct iovec));
nx_sections[n_nx_sections].iov_base = loaded_kernel + h->VirtualAddress - image_base;
nx_sections[n_nx_sections].iov_base = loaded_kernel + h->VirtualAddress;
nx_sections[n_nx_sections].iov_len = h->VirtualSize;
err = memory_mark_ro_x(memory_proto, &nx_sections[n_nx_sections]);
src/boot/pe.c
+1 -17
View File
@@ -459,7 +459,7 @@ static uint32_t get_compatibility_entry_address(const DosFileHeader *dos, const
return 0;
}
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory) {
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, size_t *ret_size_in_memory) {
assert(base);
const DosFileHeader *dos = (const DosFileHeader *) base;
@@ -470,18 +470,6 @@ EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t
if (!verify_pe(dos, pe, /* allow_compatibility= */ true))
return EFI_LOAD_ERROR;
uint64_t image_base;
switch (pe->OptionalHeader.Magic) {
case OPTHDR32_MAGIC:
image_base = pe->OptionalHeader.ImageBase32;
break;
case OPTHDR64_MAGIC:
image_base = pe->OptionalHeader.ImageBase64;
break;
default:
assert_not_reached();
}
/* When allocating we need to also consider the virtual/uninitialized data sections, so parse it out
* of the SizeOfImage field in the PE header and return it */
size_t size_in_memory = pe->OptionalHeader.SizeOfImage;
@@ -495,8 +483,6 @@ EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t
*ret_entry_point = pe->OptionalHeader.AddressOfEntryPoint;
if (ret_compat_entry_point)
*ret_compat_entry_point = 0;
if (ret_image_base)
*ret_image_base = image_base;
if (ret_size_in_memory)
*ret_size_in_memory = size_in_memory;
return EFI_SUCCESS;
@@ -511,8 +497,6 @@ EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t
*ret_entry_point = 0;
if (ret_compat_entry_point)
*ret_compat_entry_point = compat_entry_point;
if (ret_image_base)
*ret_image_base = image_base;
if (ret_size_in_memory)
*ret_size_in_memory = size_in_memory;
src/boot/pe.h
+1 -1
View File
@@ -57,7 +57,7 @@ EFI_STATUS pe_memory_locate_sections(
const char *const section_names[],
PeSectionVector sections[]);
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, uint64_t *ret_image_base, size_t *ret_size_in_memory);
EFI_STATUS pe_kernel_info(const void *base, uint32_t *ret_entry_point, uint32_t *ret_compat_entry_point, size_t *ret_size_in_memory);
EFI_STATUS pe_kernel_check_no_relocation(const void *base);