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| author | Oleg Nesterov <oleg@redhat.com> | 2012-09-16 19:31:39 +0200 |
|---|---|---|
| committer | Anton Arapov <anton@redhat.com> | 2012-10-29 11:50:14 +0100 |
| commit | f62e91e72087e6d6e4f73790922afa9981ff362f (patch) | |
| tree | 858e7c1789646deb8d867ae3e26e2bbe62364353 | |
| parent | 8e171de1a5e8d37899dd9670efb6e6a60516c7a3 (diff) | |
| download | kernel-uprobes-f62e91e72087e6d6e4f73790922afa9981ff362f.zip kernel-uprobes-f62e91e72087e6d6e4f73790922afa9981ff362f.tar.gz kernel-uprobes-f62e91e72087e6d6e4f73790922afa9981ff362f.tar.xz | |
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 a9de408..8d182bd 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) |