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.
Ensures the file being loaded has the correct data encoding, checking
'e_ident[EI_DATA]' against 'ELF_DATA'.
Besides the checks being in accordance with the ELF Specifications,
they increase the binary consistency reducing the use of malformed ones.
Signed-off-by: Geyslan G. Bem <geys...@gmail.com>
---
fs/binfmt_elf.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 571a423..326ca39 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -603,14 +603,20 @@ 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))
goto out;
+ if (loc->elf_ex.e_ident[EI_DATA] != ELF_DATA)
+ goto out;
if (!bprm->file->f_op->mmap)
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
--
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