Commit-ID: 0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 Gitweb: http://git.kernel.org/tip/0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 Author: Andy Lutomirski <[email protected]> AuthorDate: Fri, 30 Sep 2016 10:58:56 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 20 Oct 2016 09:21:41 +0200
fs/proc: Stop reporting eip and esp in /proc/PID/stat Reporting these fields on a non-current task is dangerous. If the task is in any state other than normal kernel code, they may contain garbage or even kernel addresses on some architectures. (x86_64 used to do this. I bet lots of architectures still do.) With CONFIG_THREAD_INFO_IN_TASK=y, it can OOPS, too. As far as I know, there are no use programs that make any material use of these fields, so just get rid of them. Reported-by: Jann Horn <[email protected]> Signed-off-by: Andy Lutomirski <[email protected]> Acked-by: Thomas Gleixner <[email protected]> Cc: Al Viro <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Linux API <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Tetsuo Handa <[email protected]> Cc: Tycho Andersen <[email protected]> Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> --- fs/proc/array.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index 89600fd..81818ad 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -412,10 +412,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, mm = get_task_mm(task); if (mm) { vsize = task_vsize(mm); - if (permitted) { - eip = KSTK_EIP(task); - esp = KSTK_ESP(task); - } + /* + * esp and eip are intentionally zeroed out. There is no + * non-racy way to read them without freezing the task. + * Programs that need reliable values can use ptrace(2). + */ } get_task_comm(tcomm, task);
