Commit-ID: 13f59c5e45be59665c11ddde19799b6295543b7d
Gitweb: http://git.kernel.org/tip/13f59c5e45be59665c11ddde19799b6295543b7d
Author: Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate: Mon, 28 Apr 2014 20:15:43 +0200
Committer: Oleg Nesterov <oleg@xxxxxxxxxx>
CommitDate: Wed, 30 Apr 2014 19:10:43 +0200
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@xxxxxxxxxx>
---
kernel/events/uprobes.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d1edc5e..7716c40 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;
--
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