The patch titled
Subject: fs/proc: report eip/esp in /prod/PID/stat for coredumping
has been added to the -mm tree. Its filename is
fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping.patch
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------------------------------------------------------
From: John Ogness <john.ogness@xxxxxxxxxxxxx>
Subject: fs/proc: report eip/esp in /prod/PID/stat for coredumping
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.
Link: http://lkml.kernel.org/r/87poatfwg6.fsf@xxxxxxxxxxxxx
Fixes: 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in> /proc/PID/stat")
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reported-by: Marco Felsch <marco.felsch@xxxxxxx>
Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Tycho Andersen <tycho.andersen@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/array.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN fs/proc/array.c~fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping fs/proc/array.c
--- a/fs/proc/array.c~fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping
+++ a/fs/proc/array.c
@@ -421,7 +421,15 @@ 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);
_
Patches currently in -mm which might be from john.ogness@xxxxxxxxxxxxx are
fs-proc-report-eip-esp-in-prod-pid-stat-for-coredumping.patch