* Oleg Nesterov <o...@redhat.com> [2012-09-16 19:52:42]: > write_opcode()->get_user_pages() needs FOLL_FORCE to ensure we can > read the page even if the probed task did mprotect(PROT_NONE) after > uprobe_register(). Without FOLL_WRITE, FOLL_FORCE doesn't have any > side effect but allows to read the !VM_READ memory. > > Otherwiese the subsequent uprobe_unregister()->set_orig_insn() fails > and we leak "int3". If that task does mprotect(PROT_READ | EXEC) and > execute the probed insn later it will be killed. > > Note: in fact this is also needed for _register, see the next patch. > > Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com> > --- > kernel/events/uprobes.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 14c2e99..fa1579a 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -221,7 +221,7 @@ static int write_opcode(struct arch_uprobe *auprobe, > struct mm_struct *mm, > > retry: > /* Read the page with vaddr into memory */ > - ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); > + ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); > if (ret <= 0) > return ret; > > -- > 1.5.5.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
