The field "eip" (instruction pointer) and "esp" (stack pointer) of a task
can be read from /proc/PID/stat. These fields can be interesting for
coredump.
However, these fields were disabled by commit 0a1eb2d474ed ("fs/proc: Stop
reporting eip and esp in /proc/PID/stat"), because it is generally unsafe
to do so. But it is safe for a coredumping process, and therefore
exceptions were made:
- for a coredumping thread by commit fd7d56270b52 ("fs/proc: Report
eip/esp in /prod/PID/stat for coredumping").
- for all other threads in a coredumping process by commit cb8f381f1613
("fs/proc/array.c: allow reporting eip/esp for all coredumping
threads").
The above two commits check the PF_DUMPCORE flag to determine a coredump thread
and the PF_EXITING flag for the other threads.
Unfortunately, commit 92307383082d ("coredump: Don't perform any cleanups
before dumping core") moved coredump to happen earlier and before PF_EXITING is
set. Thus, checking PF_EXITING is no longer the correct way to determine
threads in a coredumping process.
Instead of PF_EXITING, use PF_POSTCOREDUMP to determine the other threads.
Checking of PF_EXITING was added for coredumping, so it probably can now be
removed. But it doesn't hurt to keep.
Fixes: 92307383082d ("coredump: Don't perform any cleanups before dumping core")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
---
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 55ed3510d2bb..d6a0369caa93 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -500,7 +500,7 @@ 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_EXITING|PF_DUMPCORE))) {
+ if (permitted && (task->flags & (PF_EXITING|PF_DUMPCORE|PF_POSTCOREDUMP))) {
if (try_get_task_stack(task)) {
eip = KSTK_EIP(task);
esp = KSTK_ESP(task);
--
2.39.5
