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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>
This commit is contained in:
Oleg Nesterov 2012-09-30 18:54:53 +02:00
parent a5f658b71b
commit 076a365b3d
1 changed files with 6 additions and 6 deletions
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12
kernel/events/uprobes.c
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@ -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);