Messages in this thread | | | Date | Fri, 15 Jun 2012 22:06:01 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH 11/15] uprobes: move BUG_ON(UPROBE_SWBP_INSN_SIZE) from write_opcode() to install_breakpoint() |
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> > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 14c71a2..b9c61bd 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -210,7 +210,6 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, > void *vaddr_old, *vaddr_new; > struct vm_area_struct *vma; > struct uprobe *uprobe; > - unsigned long pgoff; > int ret; > retry: > /* Read the page with vaddr into memory */ > @@ -251,11 +250,7 @@ retry: > vaddr_new = kmap_atomic(new_page); > > memcpy(vaddr_new, vaddr_old, PAGE_SIZE); > - > - /* poke the new insn in, ASSUMES we don't cross page boundary */ > - pgoff = (vaddr & ~PAGE_MASK); > - BUG_ON(pgoff + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); > - memcpy(vaddr_new + pgoff, &opcode, UPROBE_SWBP_INSN_SIZE); > + memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); > > kunmap_atomic(vaddr_new); > kunmap_atomic(vaddr_old); > @@ -699,6 +694,10 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, > if (ret) > return ret; > > + /* write_opcode() assumes we don't cross page boundary */ > + BUG_ON((uprobe->offset & ~PAGE_MASK) + > + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); > + > uprobe->flags |= UPROBE_COPY_INSN; > }
I am now thinking if we really need a BUG_ON? I am now thinking I should have had a check at the start in uprobe_register() and failed the request.
Something like if ((offset & ~PAGE_MASK) + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE) return -EINVAL; -- Thanks and Regards Srikar
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