From: Oleg Nesterov Date: Mon, 28 Apr 2014 18:15:43 +0000 (+0200) Subject: uprobes: Refuse to insert a probe into MAP_SHARED vma X-Git-Tag: v3.16-rc1~25^2~14^2~1^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=13f59c5e45be59665c11ddde19799b6295543b7d;p=linux.git 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 --- diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index d1edc5e6fd03..7716c40f2c50 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -127,7 +127,7 @@ struct xol_area { */ static bool valid_vma(struct vm_area_struct *vma, bool is_register) { - vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; + vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; if (is_register) flags |= VM_WRITE;