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SubjectRe: [PATCH] fs: binfmt_elf: Add two ELF header consistency checks
From
2013/11/20 Geyslan G. Bem <geyslan@gmail.com>:
> The member 'e_ehsize' that holds the ELF header size is compared
> with the elfhdr struct size. If not equal, goes out.
> If 'e_phoff' holds 0 the object has no program header table, so
> goes out.
>
> Increasing the binary consistency reduces the use of malformed ones.
>
> Both checks are in accordance with the ELF Specifications.
>
> Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
> ---
> fs/binfmt_elf.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index 571a423..3c08f96 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -603,6 +603,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
> if (memcmp(loc->elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
> goto out;
>
> + if (loc->elf_ex.e_ehsize != sizeof(struct elfhdr))
> + goto out;
> if (loc->elf_ex.e_type != ET_EXEC && loc->elf_ex.e_type != ET_DYN)
> goto out;
> if (!elf_check_arch(&loc->elf_ex))
> @@ -611,6 +613,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
> goto out;
>
> /* Now read in all of the header information */
> + if (loc->elf_ex.e_phoff == 0)
> + goto out;
> if (loc->elf_ex.e_phentsize != sizeof(struct elf_phdr))
> goto out;
> if (loc->elf_ex.e_phnum < 1 ||
> --
> 1.8.4.2
>

PATCH v2 Sent:
[PATCH v2] fs: binfmt_elf: Add ELF header consistency checks

--
Regards,

Geyslan G. Bem
hackingbits.com


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