From: Oleg Nesterov Date: Sun, 29 Jul 2012 18:22:12 +0000 (+0200) Subject: uprobes: Don't recheck vma/f_mapping in write_opcode() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f403072c6108e15f319a4a5036b650c77760522c;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git uprobes: Don't recheck vma/f_mapping in write_opcode() write_opcode() rechecks valid_vma() and ->f_mapping, this is pointless. The caller, register_for_each_vma() or uprobe_mmap(), has already done these checks under mmap_sem. To clarify, uprobe_mmap() checks valid_vma() only, but we can rely on build_probe_list(vm_file->f_mapping->host). Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju Cc: Anton Arapov Cc: Srikar Dronamraju Link: http://lkml.kernel.org/r/20120729182212.GA20304@redhat.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index f93532748bca..a2b32a51d0a2 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -206,33 +206,16 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t opcode) { struct page *old_page, *new_page; - struct address_space *mapping; void *vaddr_old, *vaddr_new; struct vm_area_struct *vma; - struct uprobe *uprobe; int ret; + retry: /* Read the page with vaddr into memory */ ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); if (ret <= 0) return ret; - ret = -EINVAL; - - /* - * We are interested in text pages only. Our pages of interest - * should be mapped for read and execute only. We desist from - * adding probes in write mapped pages since the breakpoints - * might end up in the file copy. - */ - if (!valid_vma(vma, is_swbp_insn(&opcode))) - goto put_out; - - uprobe = container_of(auprobe, struct uprobe, arch); - mapping = uprobe->inode->i_mapping; - if (mapping != vma->vm_file->f_mapping) - goto put_out; - ret = -ENOMEM; new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); if (!new_page)