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loader: x86_64: elf: Avoid reading beyond file end #125

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Merged
rbradford merged 1 commit into from
Dec 6, 2022
Merged

loader: x86_64: elf: Avoid reading beyond file end #125

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13 changes: 6 additions & 7 deletions src/loader/x86_64/elf/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -217,8 +217,8 @@ impl KernelLoader for Elf {
.map_err(|_| Error::SeekElfStart)?;

let mut ehdr = elf::Elf64_Ehdr::default();
ehdr.as_bytes()
.read_from(0, kernel_image, mem::size_of::<elf::Elf64_Ehdr>())
kernel_image
.read_exact(ehdr.as_mut_slice())
.map_err(|_| Error::ReadElfHeader)?;

// Sanity checks.
Expand Down Expand Up @@ -246,12 +246,11 @@ impl KernelLoader for Elf {
.seek(SeekFrom::Start(ehdr.e_phoff))
.map_err(|_| Error::SeekProgramHeader)?;

let phdr_sz = mem::size_of::<elf::Elf64_Phdr>();
let mut phdrs: Vec<elf::Elf64_Phdr> = vec![];
for _ in 0usize..ehdr.e_phnum as usize {
let mut phdr = elf::Elf64_Phdr::default();
phdr.as_bytes()
.read_from(0, kernel_image, phdr_sz)
kernel_image
.read_exact(phdr.as_mut_slice())
.map_err(|_| Error::ReadProgramHeader)?;
phdrs.push(phdr);
}
Expand Down Expand Up @@ -335,8 +334,8 @@ where
let nhdr_sz = mem::size_of::<elf::Elf64_Nhdr>();

while read_size < phdr.p_filesz as usize {
nhdr.as_bytes()
.read_from(0, kernel_image, nhdr_sz)
kernel_image
.read_exact(nhdr.as_mut_slice())
.map_err(|_| Error::ReadNoteHeader)?;

// Check if the note header's name and type match the ones specified by the PVH ABI.
Expand Down