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authorOleg Nesterov <oleg@redhat.com>2012-09-16 19:31:39 +0200
committerAnton Arapov <anton@redhat.com>2012-10-29 11:50:14 +0100
commitf62e91e72087e6d6e4f73790922afa9981ff362f (patch)
tree858e7c1789646deb8d867ae3e26e2bbe62364353
parent8e171de1a5e8d37899dd9670efb6e6a60516c7a3 (diff)
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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.c13
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)