From: Hugh Dickins Date: Thu, 10 Jul 2008 20:19:20 +0000 (+0100) Subject: exec: fix stack excutability without PT_GNU_STACK X-Git-Tag: v2.6.26~27 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=96a8e13ed44e380fc2bb6c711d74d5ba698c00b2;p=linux-2.6 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 Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- diff --git a/fs/exec.c b/fs/exec.c index da94a6f05d..fd9234379e 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -610,7 +610,7 @@ int setup_arg_pages(struct linux_binprm *bprm, bprm->exec -= stack_shift; down_write(&mm->mmap_sem); - vm_flags = vma->vm_flags; + vm_flags = VM_STACK_FLAGS; /* * Adjust stack execute permissions; explicitly enable for