diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2012-09-16 19:31:39 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2012-09-29 21:21:54 +0200 |
| commit | e40cfce626a5537994058ee9a940dcfdc0f68ef0 (patch) | |
| tree | ce9a24a51906fb3437ea0f08851e4dfb4671aa0b | |
| parent | 78a320542e6cdb2800cd736b2d136e4261d34f43 (diff) | |
uprobes: Restrict valid_vma(false) to skip VM_SHARED vmas
valid_vma(false) ignores ->vm_flags, this is not actually right.
We should never try to write into MAP_SHARED mapping, this can
confuse an apllication which actually writes to ->vm_file.
With this patch valid_vma(false) ignores VM_WRITE only but checks
other (immutable) bits checked by valid_vma(true). This can also
speedup uprobe_munmap() and uprobe_unregister().
Note: even after this patch _unregister can confuse the probed
application if it does mprotect(PROT_WRITE) after _register and
installs "int3", but this is hardly possible to avoid and this
doesn't differ from gdb case.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
| -rw-r--r-- | kernel/events/uprobes.c | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index a9de40815391..8d182bdecc2e 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -100,17 +100,12 @@ struct uprobe { */ static bool valid_vma(struct vm_area_struct *vma, bool is_register) { - if (!vma->vm_file) - return false; - - if (!is_register) - return true; + vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; - if ((vma->vm_flags & (VM_HUGETLB | VM_WRITE | VM_MAYEXEC | VM_SHARED)) - == VM_MAYEXEC) - return true; + if (is_register) + flags |= VM_WRITE; - return false; + return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; } static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |