tree 62eb5b26a3cfe678f82f9d5c131b08114950f551
parent f8804d39462dc019ae9d1a6e4d45512e9dfec2bf
author Hugh Dickins <hugh@veritas.com> 1215721160 +0100
committer Linus Torvalds <torvalds@linux-foundation.org> 1215721543 -0700

exec: fix stack excutability without PT_GNU_STACK

Kernel Bugzilla #11063 points out that on some architectures (e.g. x86_32)
exec'ing an ELF without a PT_GNU_STACK program header should default to an
executable stack; but this got broken by the unlimited argv feature because
stack vma is now created before the right personality has been established:
so breaking old binaries using nested function trampolines.

Therefore re-evaluate VM_STACK_FLAGS in setup_arg_pages, where stack
vm_flags used to be set, before the mprotect_fixup.  Checking through
our existing VM_flags, none would have changed since insert_vm_struct:
so this seems safer than finding a way through the personality labyrinth.

Reported-by: pageexec@freemail.hu
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>