c/r: prctl: less paranoid prctl_set_mm_exe_file() (4229fb1d) · Commits · 戴 / test

"no other files mapped" requirement from my previous patch (c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal) is too paranoid, it forbids operation even if there mapped one shared-anon vma. Let's check that current mm->exe_file already unmapped, in this case exe_file symlink already outdated and its changing is reasonable. Plus, this patch fixes exit code in case operation success. Signed-off-by:

Konstantin Khlebnikov <khlebnikov@openvz.org> Reported-by:

Cyrill Gorcunov <gorcunov@openvz.org> Tested-by:

Cyrill Gorcunov <gorcunov@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Kees Cook <keescook@chromium.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Pavel Emelyanov <xemul@parallels.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/sys.c

+10 −6

Original line number	Diff line number	Diff line
		@@ -1788,7 +1788,6 @@ SYSCALL_DEFINE1(umask, int, mask)
		#ifdef CONFIG_CHECKPOINT_RESTORE
		static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
		{
		struct vm_area_struct *vma;
		struct file *exe_file;
		struct dentry *dentry;
		int err;
		@@ -1816,12 +1815,16 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
		down_write(&mm->mmap_sem);

		/*
		* Forbid mm->exe_file change if there are mapped other files.
		* Forbid mm->exe_file change if old file still mapped.
		*/
		err = -EBUSY;
		for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (vma->vm_file && !path_equal(&vma->vm_file->f_path,
		&exe_file->f_path))
		if (mm->exe_file) {
		struct vm_area_struct *vma;

		for (vma = mm->mmap; vma; vma = vma->vm_next)
		if (vma->vm_file &&
		path_equal(&vma->vm_file->f_path,
		&mm->exe_file->f_path))
		goto exit_unlock;
		}

		@@ -1835,6 +1838,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
		if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
		goto exit_unlock;

		err = 0;
		set_mm_exe_file(mm, exe_file);
		exit_unlock:
		up_write(&mm->mmap_sem);

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