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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 cda540ace6 "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>
hifive-unleashed-5.1
Oleg Nesterov 2014-04-28 20:15:43 +02:00
parent 927d687480
commit 13f59c5e45
1 changed files with 1 additions and 1 deletions
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2
kernel/events/uprobes.c
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@ -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;