uprobes: Do not delete uprobe if uprobe_unregister() fails (076a365b) · Commits · 戴 / test

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>

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);

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