Messages in this thread Patch in this message | | | Date | Thu, 20 Oct 2016 04:13:20 -0700 | From | tip-bot for Andy Lutomirski <> | Subject | [tip:mm/urgent] fs/proc: Stop reporting eip and esp in /proc/PID/stat |
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Commit-ID: 0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 Gitweb: http://git.kernel.org/tip/0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 Author: Andy Lutomirski <luto@kernel.org> AuthorDate: Fri, 30 Sep 2016 10:58:56 -0700 Committer: Ingo Molnar <mingo@kernel.org> 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 <jann@thejh.net> Signed-off-by: Andy Lutomirski <luto@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Linux API <linux-api@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: Tycho Andersen <tycho.andersen@canonical.com> Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> --- 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);
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