From: Kees Cook keescook@chromium.org
commit 7be3cb019db1cbd5fd5ffe6d64a23fefa4b6f229 upstream.
When brk was moved for binaries without an interpreter, it should have been limited to ET_DYN only. In other words, the special case was an ET_DYN that lacks an INTERP, not just an executable that lacks INTERP. The bug manifested for giant static executables, where the brk would end up in the middle of the text area on 32-bit architectures.
Reported-and-tested-by: Richard Kojedzinszky richard@kojedz.in Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/binfmt_elf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1107,7 +1107,8 @@ static int load_elf_binary(struct linux_ * (since it grows up, and may collide early with the stack * growing down), and into the unused ELF_ET_DYN_BASE region. */ - if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && !interpreter) + if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && + loc->elf_ex.e_type == ET_DYN && !interpreter) current->mm->brk = current->mm->start_brk = ELF_ET_DYN_BASE;