diff options
| author | Yin Fengwei <fengwei_yin@linux.alibaba.com> | 2025-07-17 19:01:08 +0800 |
|---|---|---|
| committer | Kees Cook <kees@kernel.org> | 2025-07-17 16:29:32 -0700 |
| commit | 8030790477e839b94a10032c490132e47926cb02 (patch) | |
| tree | 8dfcc17854d19e04f9e25aab025b25b9ff168213 | |
| parent | a55128d392e86507a0e6672ebcdf20d1dd77744b (diff) | |
binfmt_elf: remove the 4k limitation of program header size
We have assembly code generated by a script. GCC successfully compiles
it. However, the kernel cannot load it on an ARM64 platform with a 4K
page size. In contrast, the same ELF file loads correctly on the same
platform with a 64K page size.
The root cause is the Linux kernel's ELF_MIN_ALIGN limitation on the
program headers of ELF files. The ELF file contains 78 program headers
(the script inserts many holes when generating the assembly code). On
ARM64 with a 4K page size, the ELF_MIN_ALLIGN enforces a maximum of 74
program headers, causing the ELF file to fail. However, with a 64K page
size, the ELF_MIN_ALIGN is relaxed to over 1,184 program headers, allowing
the file to run correctly.
Cook kindly identified[1] that this limitation was introduced in
Linux-0.99.15f without an explanation for its purpose.
The ELF specification does not impose such a restriction on program
headers. Removing the ELF_MIN_ALIGN limitation on program headers to
align with the ELF spec. After removing ELF_MIN_ALIGN limitation,
64K size limitation still exist which should be sufficient.
Suggested-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/linux-mm/202506270854.A729825@keescook/ [1]
Signed-off-by: Yin Fengwei <fengwei_yin@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250717110108.55586-1-fengwei_yin@linux.alibaba.com
Signed-off-by: Kees Cook <kees@kernel.org>
| -rw-r--r-- | fs/binfmt_elf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 92cf005468b5..caeddccaa1fe 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -519,7 +519,7 @@ static struct elf_phdr *load_elf_phdrs(const struct elfhdr *elf_ex, /* Sanity check the number of program headers... */ /* ...and their total size. */ size = sizeof(struct elf_phdr) * elf_ex->e_phnum; - if (size == 0 || size > 65536 || size > ELF_MIN_ALIGN) + if (size == 0 || size > 65536) goto out; elf_phdata = kmalloc(size, GFP_KERNEL); |