uprobes: Do not delete uprobe if uprobe_unregister() fails
delete_uprobe() must not be called if register_for_each_vma(false)
fails to remove all breakpoints, __uprobe_unregister() is correct.
The problem is that register_for_each_vma(false) always returns 0
and thus this logic does not work.
1. Change verify_opcode() to return 0 rather than -EINVAL when
unregister detects the !is_swbp insn, we can treat this case
as success and currently unregister paths ignore the error
code anyway.
2. Change remove_breakpoint() to propagate the error code from
write_opcode().
3. Change register_for_each_vma(is_register => false) to remove
as much breakpoints as possible but return non-zero if
remove_breakpoint() fails at least once.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 588a557..a1b466d 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -203,7 +203,7 @@
return 0;
} else {
if (!is_swbp) /* unregister: was it changed by us? */
- return -EINVAL;
+ return 0;
}
return 1;
@@ -616,15 +616,15 @@
return ret;
}
-static void
+static int
remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
{
/* can happen if uprobe_register() fails */
if (!test_bit(MMF_HAS_UPROBES, &mm->flags))
- return;
+ return 0;
set_bit(MMF_RECALC_UPROBES, &mm->flags);
- set_orig_insn(&uprobe->arch, mm, vaddr);
+ return set_orig_insn(&uprobe->arch, mm, vaddr);
}
/*
@@ -740,7 +740,7 @@
struct mm_struct *mm = info->mm;
struct vm_area_struct *vma;
- if (err)
+ if (err && is_register)
goto free;
down_write(&mm->mmap_sem);
@@ -756,7 +756,7 @@
if (is_register)
err = install_breakpoint(uprobe, mm, vma, info->vaddr);
else
- remove_breakpoint(uprobe, mm, info->vaddr);
+ err |= remove_breakpoint(uprobe, mm, info->vaddr);
unlock:
up_write(&mm->mmap_sem);
