diff options
| author | John Ogness | 2017-09-14 11:42:17 +0200 |
|---|---|---|
| committer | Thomas Gleixner | 2017-09-15 23:31:16 +0200 |
| commit | fd7d56270b526ca3ed0c224362e3c64a0f86687a (patch) | |
| tree | 21158ebee7055e5064ea6a75a3a4f186416a19ca | |
| parent | 97dab2ae7e8473a821f72a039ead0f36b12ba22d (diff) | |
fs/proc: Report eip/esp in /prod/PID/stat for coredumping
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: stable@vger.kernel.org
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>
| -rw-r--r-- | fs/proc/array.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index 88c355574aa0..525157ca25cb 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -62,6 +62,7 @@ #include <linux/mman.h> #include <linux/sched/mm.h> #include <linux/sched/numa_balancing.h> +#include <linux/sched/task_stack.h> #include <linux/sched/task.h> #include <linux/sched/cputime.h> #include <linux/proc_fs.h> @@ -421,7 +422,15 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, * 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); |