uprobes: Refuse to insert a probe into MAP_SHARED vma
authorOleg Nesterov <oleg@redhat.com>
Mon, 28 Apr 2014 18:15:43 +0000 (20:15 +0200)
committerOleg Nesterov <oleg@redhat.com>
Wed, 30 Apr 2014 17:10:43 +0000 (19:10 +0200)
commit13f59c5e45be59665c11ddde19799b6295543b7d
tree86b9999733f0826f2bad3e4d2285d9585f3a9f67
parent927d687480ab7e43d73a003bab58803fc67717d9
uprobes: Refuse to insert a probe into MAP_SHARED vma

valid_vma() rejects the VM_SHARED vmas, but this still allows to insert
a probe into the MAP_SHARED but not VM_MAYWRITE vma.

Currently this is fine, such a mapping doesn't really differ from the
private read-only mmap except mprotect(PROT_WRITE) won't work. However,
get_user_pages(FOLL_WRITE | FOLL_FORCE) doesn't allow to COW in this
case, and it would be safer to follow the same conventions as mm even
if currently this happens to work.

After the recent cda540ace6a1 "mm: get_user_pages(write,force) refuse
to COW in shared areas" only uprobes can insert an anon page into the
shared file-backed area, lets stop this and change valid_vma() to check
VM_MAYSHARE instead.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
kernel/events/uprobes.c