From 40c7fd3fdfba97a18724a0b96d132335fd419e98 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 8 Apr 2021 11:46:12 +0200 Subject: block: Fix sys_ioprio_set(.which=IOPRIO_WHO_PGRP) task iteration do_each_pid_thread() { } while_each_pid_thread() is a double loop and thus break doesn't work as expected. Also, it should be used under tasklist_lock because otherwise we can race against change_pid() for PGID/SID. Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/YG7Q5C4Rb5dx5GFx@hirez.programming.kicks-ass.net Signed-off-by: Jens Axboe --- block/ioprio.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/ioprio.c b/block/ioprio.c index 364d2294ba90..bee628f9f1b2 100644 --- a/block/ioprio.c +++ b/block/ioprio.c @@ -119,11 +119,17 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) pgrp = task_pgrp(current); else pgrp = find_vpid(who); + + read_lock(&tasklist_lock); do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { ret = set_task_ioprio(p, ioprio); - if (ret) - break; + if (ret) { + read_unlock(&tasklist_lock); + goto out; + } } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); + read_unlock(&tasklist_lock); + break; case IOPRIO_WHO_USER: uid = make_kuid(current_user_ns(), who); @@ -153,6 +159,7 @@ free_uid: ret = -EINVAL; } +out: rcu_read_unlock(); return ret; } -- cgit v1.2.3