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From: Stefano Garzarella <sgarzare@redhat.com>
To: virtualization@lists.linux-foundation.org
Cc: Jason Wang <jasowang@redhat.com>,
	netdev@vger.kernel.org, Zhu Lingshan <lingshan.zhu@intel.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx
Date: Thu, 11 Mar 2021 14:52:56 +0100	[thread overview]
Message-ID: <20210311135257.109460-2-sgarzare@redhat.com> (raw)
In-Reply-To: <20210311135257.109460-1-sgarzare@redhat.com>

When the 'v->config_ctx' eventfd_ctx reference is released we didn't
set it to NULL. So if the same character device (e.g. /dev/vhost-vdpa-0)
is re-opened, the 'v->config_ctx' is invalid and calling again
vhost_vdpa_config_put() causes use-after-free issues like the
following refcount_t underflow:

    refcount_t: underflow; use-after-free.
    WARNING: CPU: 2 PID: 872 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0
    RIP: 0010:refcount_warn_saturate+0xae/0xf0
    Call Trace:
     eventfd_ctx_put+0x5b/0x70
     vhost_vdpa_release+0xcd/0x150 [vhost_vdpa]
     __fput+0x8e/0x240
     ____fput+0xe/0x10
     task_work_run+0x66/0xa0
     exit_to_user_mode_prepare+0x118/0x120
     syscall_exit_to_user_mode+0x21/0x50
     ? __x64_sys_close+0x12/0x40
     do_syscall_64+0x45/0x50
     entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 776f395004d8 ("vhost_vdpa: Support config interrupt in vdpa")
Cc: lingshan.zhu@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 drivers/vhost/vdpa.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index ef688c8c0e0e..00796e4ecfdf 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -308,8 +308,10 @@ static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
 
 static void vhost_vdpa_config_put(struct vhost_vdpa *v)
 {
-	if (v->config_ctx)
+	if (v->config_ctx) {
 		eventfd_ctx_put(v->config_ctx);
+		v->config_ctx = NULL;
+	}
 }
 
 static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp)
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Stefano Garzarella <sgarzare@redhat.com>
To: virtualization@lists.linux-foundation.org
Cc: kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Zhu Lingshan <lingshan.zhu@intel.com>
Subject: [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx
Date: Thu, 11 Mar 2021 14:52:56 +0100	[thread overview]
Message-ID: <20210311135257.109460-2-sgarzare@redhat.com> (raw)
In-Reply-To: <20210311135257.109460-1-sgarzare@redhat.com>

When the 'v->config_ctx' eventfd_ctx reference is released we didn't
set it to NULL. So if the same character device (e.g. /dev/vhost-vdpa-0)
is re-opened, the 'v->config_ctx' is invalid and calling again
vhost_vdpa_config_put() causes use-after-free issues like the
following refcount_t underflow:

    refcount_t: underflow; use-after-free.
    WARNING: CPU: 2 PID: 872 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0
    RIP: 0010:refcount_warn_saturate+0xae/0xf0
    Call Trace:
     eventfd_ctx_put+0x5b/0x70
     vhost_vdpa_release+0xcd/0x150 [vhost_vdpa]
     __fput+0x8e/0x240
     ____fput+0xe/0x10
     task_work_run+0x66/0xa0
     exit_to_user_mode_prepare+0x118/0x120
     syscall_exit_to_user_mode+0x21/0x50
     ? __x64_sys_close+0x12/0x40
     do_syscall_64+0x45/0x50
     entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 776f395004d8 ("vhost_vdpa: Support config interrupt in vdpa")
Cc: lingshan.zhu@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 drivers/vhost/vdpa.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index ef688c8c0e0e..00796e4ecfdf 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -308,8 +308,10 @@ static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
 
 static void vhost_vdpa_config_put(struct vhost_vdpa *v)
 {
-	if (v->config_ctx)
+	if (v->config_ctx) {
 		eventfd_ctx_put(v->config_ctx);
+		v->config_ctx = NULL;
+	}
 }
 
 static long vhost_vdpa_set_config_call(struct vhost_vdpa *v, u32 __user *argp)
-- 
2.29.2

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  reply	other threads:[~2021-03-11 13:53 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-11 13:52 [PATCH 0/2] vhost-vdpa: fix issues around v->config_ctx handling Stefano Garzarella
2021-03-11 13:52 ` Stefano Garzarella
2021-03-11 13:52 ` Stefano Garzarella [this message]
2021-03-11 13:52   ` [PATCH 1/2] vhost-vdpa: fix use-after-free of v->config_ctx Stefano Garzarella
2021-03-12  1:37   ` Zhu, Lingshan
2021-03-12  6:33   ` Jason Wang
2021-03-12  6:33     ` Jason Wang
2021-03-11 13:52 ` [PATCH 2/2] vhost-vdpa: set v->config_ctx to NULL if eventfd_ctx_fdget() fails Stefano Garzarella
2021-03-11 13:52   ` Stefano Garzarella
2021-03-12  6:34   ` Jason Wang
2021-03-12  6:34     ` Jason Wang
2021-03-11 16:42 ` [PATCH 0/2] vhost-vdpa: fix issues around v->config_ctx handling Michael S. Tsirkin
2021-03-11 16:42   ` Michael S. Tsirkin

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