linux-kernel - [PATCH] proc: report eip and esp for all threads when coredumping

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Date:   Wed, 22 May 2019 18:16:14 +0200
From:   Jan Luebbe <jlu@...gutronix.de>
To:     Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        John Ogness <john.ogness@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>
Cc:     kernel@...gutronix.de, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, Jan Luebbe <jlu@...gutronix.de>
Subject: [PATCH] proc: report eip and esp for all threads when coredumping

Commit 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in
/proc/PID/stat") stopped reporting eip/esp and commit fd7d56270b52
("fs/proc: Report eip/esp in /prod/PID/stat for coredumping")
reintroduced the feature to fix a regression with userspace core dump
handlers (such as minicoredumper).

Because PF_DUMPCORE is only set for the primary thread, this didn't fix
the original problem for secondary threads. This commit checks
mm->core_state instead, as already done for /proc/<pid>/status in
task_core_dumping(). As we have a mm_struct available here anyway, this
seems to be a clean solution.

Signed-off-by: Jan Luebbe <jlu@...gutronix.de>
---
 fs/proc/array.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 2edbb657f859..b76b1e29fc36 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -462,7 +462,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 		 * 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)) {
+		if (permitted && (!!mm->core_state)) {
 			if (try_get_task_stack(task)) {
 				eip = KSTK_EIP(task);
 				esp = KSTK_ESP(task);
-- 
2.11.0