tree da2c69d053b7555c15e1adb5e6d901c2afab8ad8
parent db023ea595015058270be6a62fe60a7b6b5c50d7
author Oleg Nesterov <oleg@redhat.com> 1347808806 +0200
committer Oleg Nesterov <oleg@redhat.com> 1348946513 +0200

uprobes: Change write_opcode() to use FOLL_FORCE

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 <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>