From: Christian Brauner Date: Tue, 28 Oct 2025 08:45:47 +0000 (+0100) Subject: pidfs: fix PIDFD_INFO_COREDUMP handling X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fe0e6ce3fd65bac9854b3b0c25dcb083f9b7beb0;p=thirdparty%2Flinux.git pidfs: fix PIDFD_INFO_COREDUMP handling When PIDFD_INFO_COREDUMP is requested we raise it unconditionally in the returned mask even if no coredump actually did take place. This was done because we assumed that the later check whether ->coredump_mask as non-zero detects that it is zero and then retrieves the dumpability settings from the task's mm. This has issues though becuase there are tasks that might not have any mm. Also it's just not very cleanly implemented. Fix this. Link: https://patch.msgid.link/20251028-work-coredump-signal-v1-2-ca449b7b7aa0@kernel.org Reviewed-by: Alexander Mikhalitsyn Reviewed-by: Oleg Nesterov Signed-off-by: Christian Brauner --- diff --git a/fs/pidfs.c b/fs/pidfs.c index c2f0b7091cd7d..c0f410903c3f3 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -335,8 +335,9 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg) } if (mask & PIDFD_INFO_COREDUMP) { - kinfo.mask |= PIDFD_INFO_COREDUMP; kinfo.coredump_mask = READ_ONCE(attr->__pei.coredump_mask); + if (kinfo.coredump_mask) + kinfo.mask |= PIDFD_INFO_COREDUMP; } task = get_pid_task(pid, PIDTYPE_PID); @@ -355,12 +356,13 @@ static long pidfd_info(struct file *file, unsigned int cmd, unsigned long arg) if (!c) return -ESRCH; - if ((kinfo.mask & PIDFD_INFO_COREDUMP) && !(kinfo.coredump_mask)) { + if ((mask & PIDFD_INFO_COREDUMP) && !kinfo.coredump_mask) { guard(task_lock)(task); if (task->mm) { unsigned long flags = __mm_flags_get_dumpable(task->mm); kinfo.coredump_mask = pidfs_coredump_mask(flags); + kinfo.mask |= PIDFD_INFO_COREDUMP; } }