linux-kernel - [PATCH 4.19 249/361] userfaultfd: disable irqs when taking the waitqueue lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 11 Nov 2018 14:19:56 -0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.19 249/361] userfaultfd: disable irqs when taking the waitqueue lock

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <hch@....de>

commit ae62c16e105a869524afcf8a07ee85c5ae5d0479 upstream.

userfaultfd contains howe-grown locking of the waitqueue lock, and does
not disable interrupts.  This relies on the fact that no one else takes it
from interrupt context and violates an invariat of the normal waitqueue
locking scheme.  With aio poll it is easy to trigger other locks that
disable interrupts (or are called from interrupt context).

Link: http://lkml.kernel.org/r/20181018154101.18750-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Andrea Arcangeli <aarcange@...hat.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: <stable@...r.kernel.org>	[4.19.x]
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/userfaultfd.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1026,7 +1026,7 @@ static ssize_t userfaultfd_ctx_read(stru
 	struct userfaultfd_ctx *fork_nctx = NULL;
 
 	/* always take the fd_wqh lock before the fault_pending_wqh lock */
-	spin_lock(&ctx->fd_wqh.lock);
+	spin_lock_irq(&ctx->fd_wqh.lock);
 	__add_wait_queue(&ctx->fd_wqh, &wait);
 	for (;;) {
 		set_current_state(TASK_INTERRUPTIBLE);
@@ -1112,13 +1112,13 @@ static ssize_t userfaultfd_ctx_read(stru
 			ret = -EAGAIN;
 			break;
 		}
-		spin_unlock(&ctx->fd_wqh.lock);
+		spin_unlock_irq(&ctx->fd_wqh.lock);
 		schedule();
-		spin_lock(&ctx->fd_wqh.lock);
+		spin_lock_irq(&ctx->fd_wqh.lock);
 	}
 	__remove_wait_queue(&ctx->fd_wqh, &wait);
 	__set_current_state(TASK_RUNNING);
-	spin_unlock(&ctx->fd_wqh.lock);
+	spin_unlock_irq(&ctx->fd_wqh.lock);
 
 	if (!ret && msg->event == UFFD_EVENT_FORK) {
 		ret = resolve_userfault_fork(ctx, fork_nctx, msg);