lkml.org 
[lkml]   [2017]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.9 03/64] fs/proc: Report eip/esp in /prod/PID/stat for coredumping
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: John Ogness <john.ogness@linutronix.de>

    commit fd7d56270b526ca3ed0c224362e3c64a0f86687a upstream.

    Commit 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in
    /proc/PID/stat") stopped reporting eip/esp because it is
    racy and dangerous for executing tasks. The comment adds:

    As far as I know, there are no use programs that make any
    material use of these fields, so just get rid of them.

    However, existing userspace core-dump-handler applications (for
    example, minicoredumper) are using these fields since they
    provide an excellent cross-platform interface to these valuable
    pointers. So that commit introduced a user space visible
    regression.

    Partially revert the change and make the readout possible for
    tasks with the proper permissions and only if the target task
    has the PF_DUMPCORE flag set.

    Fixes: 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in> /proc/PID/stat")
    Reported-by: Marco Felsch <marco.felsch@preh.de>
    Signed-off-by: John Ogness <john.ogness@linutronix.de>
    Reviewed-by: Andy Lutomirski <luto@kernel.org>
    Cc: Tycho Andersen <tycho.andersen@canonical.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Linux API <linux-api@vger.kernel.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Link: http://lkml.kernel.org/r/87poatfwg6.fsf@linutronix.de
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/proc/array.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    --- a/fs/proc/array.c
    +++ b/fs/proc/array.c
    @@ -60,6 +60,7 @@
    #include <linux/tty.h>
    #include <linux/string.h>
    #include <linux/mman.h>
    +#include <linux/sched.h>
    #include <linux/proc_fs.h>
    #include <linux/ioport.h>
    #include <linux/uaccess.h>
    @@ -416,7 +417,15 @@ static int do_task_stat(struct seq_file
    * 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).
    + *
    + * The only exception is if the task is core dumping because
    + * a program is not able to use ptrace(2) in that case. It is
    + * safe because the task has stopped executing permanently.
    */
    + if (permitted && (task->flags & PF_DUMPCORE)) {
    + eip = KSTK_EIP(task);
    + esp = KSTK_ESP(task);
    + }
    }

    get_task_comm(tcomm, task);

    \
     
     \ /
      Last update: 2017-10-03 15:05    [W:4.294 / U:0.108 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site