[PATCH 4.19 32/72] fs/proc/array.c: allow reporting eip/esp for all coredumping threads

From: Greg Kroah-Hartman
Date: Tue Jul 02 2019 - 04:06:30 EST

From: John Ogness <john.ogness@xxxxxxxxxxxxx>

commit cb8f381f1613cafe3aec30809991cd56e7135d92 upstream.

0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat")
stopped reporting eip/esp and 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. Allow reporting the eip/esp
for all threads by checking for PF_EXITING as well. This is set for all
the other threads when they are killed. coredump_wait() waits for all the
tasks to become inactive before proceeding to invoke a core dumper.

Link: http://lkml.kernel.org/r/87y32p7i7a.fsf@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190522161614.628-1-jlu@xxxxxxxxxxxxxx
Fixes: fd7d56270b526ca3 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping")
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reported-by: Jan Luebbe <jlu@xxxxxxxxxxxxxx>
Tested-by: Jan Luebbe <jlu@xxxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/proc/array.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -452,7 +452,7 @@ static int do_task_stat(struct seq_file
* 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 && (task->flags & (PF_EXITING|PF_DUMPCORE))) {
if (try_get_task_stack(task)) {
eip = KSTK_EIP(task);
esp = KSTK_ESP(task);