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Commit f403072c authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
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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: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/20120729182212.GA20304@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 35d56ca9

kernel/events/uprobes.c

+1 −18
Original line number Diff line number Diff line
@@ -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)