Messages in this thread Patch in this message | | | Date | Mon, 28 Apr 2014 21:16:22 +0200 | From | Oleg Nesterov <> | Subject | [PATCH] uprobes: Refuse to insert a probe into MAP_SHARED vma |
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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 | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
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; -- 1.5.5.1
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