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Commit 076a365b authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent a5f658b7

kernel/events/uprobes.c

+6 −6
Original line number Diff line number Diff line
@@ -203,7 +203,7 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t 
			return 0;

	} else {

		if (!is_swbp)		/* unregister: was it changed by us? */

			return -EINVAL;

			return 0;

	}



	return 1;
@@ -616,15 +616,15 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 
	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 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 
		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 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 
		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);