Hi!
[ Upstream commit 2a97388a807b6ab5538aa8f8537b2463c6988bd2 ]
ELF loader uses "randomize_va_space" twice. It is sysctl and can change at any moment, so 2 loads could see 2 different values in theory with unpredictable consequences.
Issue exactly one load for consistent value across one exec.
Signed-off-by: Alexey Dobriyan adobriyan@gmail.com Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183 Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org
fs/binfmt_elf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index c41c568ad1b8a..af8830878fa0b 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -876,7 +876,8 @@ static int load_elf_binary(struct linux_binprm *bprm) if (elf_read_implies_exec(loc->elf_ex, executable_stack)) current->personality |= READ_IMPLIES_EXEC;
- if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
- const int snapshot_randomize_va_space = READ_ONCE(randomize_va_space);
- if (!(current->personality & ADDR_NO_RANDOMIZE) && snapshot_randomize_va_space) current->flags |= PF_RANDOMIZE;
setup_new_exec(bprm);
We normally put variable declaration at start of the function. I'd not be surprised if this broke with older compilers.
Best regards, Pavel