[PATCH 088/133] virtio: console: fix race with port unplug and open/close
3.8.13.7 -stable review patch. If anyone has any objections, please let me
know.
--
From: Amit Shah
commit 057b82be3ca3d066478e43b162fc082930a746c9 upstream.
There's a window between find_port_by_devt() returning a port and us
taking a kref on the port, where the port could get unplugged. Fix it
by taking the reference in find_port_by_devt() itself.
Problem reported and analyzed by Mateusz Guzik.
Reported-by: Mateusz Guzik
Signed-off-by: Amit Shah
Signed-off-by: Rusty Russell
Signed-off-by: Kamal Mostafa
---
drivers/char/virtio_console.c | 13 ++---
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3e338a7..ff015e7 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -278,9 +278,12 @@ static struct port *find_port_by_devt_in_portdev(struct
ports_device *portdev,
unsigned long flags;
spin_lock_irqsave(>ports_lock, flags);
- list_for_each_entry(port, >ports, list)
- if (port->cdev->dev == dev)
+ list_for_each_entry(port, >ports, list) {
+ if (port->cdev->dev == dev) {
+ kref_get(>kref);
goto out;
+ }
+ }
port = NULL;
out:
spin_unlock_irqrestore(>ports_lock, flags);
@@ -1042,14 +1045,10 @@ static int port_fops_open(struct inode *inode, struct
file *filp)
struct port *port;
int ret;
+ /* We get the port with a kref here */
port = find_port_by_devt(cdev->dev);
filp->private_data = port;
- /* Prevent against a port getting hot-unplugged at the same time */
- spin_lock_irq(>portdev->ports_lock);
- kref_get(>kref);
- spin_unlock_irq(>portdev->ports_lock);
-
/*
* Don't allow opening of console port devices -- that's done
* via /dev/hvc
--
1.8.1.2
--
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[PATCH 088/133] virtio: console: fix race with port unplug and open/close
3.8.13.7 -stable review patch. If anyone has any objections, please let me
know.
--
From: Amit Shah amit.s...@redhat.com
commit 057b82be3ca3d066478e43b162fc082930a746c9 upstream.
There's a window between find_port_by_devt() returning a port and us
taking a kref on the port, where the port could get unplugged. Fix it
by taking the reference in find_port_by_devt() itself.
Problem reported and analyzed by Mateusz Guzik.
Reported-by: Mateusz Guzik mgu...@redhat.com
Signed-off-by: Amit Shah amit.s...@redhat.com
Signed-off-by: Rusty Russell ru...@rustcorp.com.au
Signed-off-by: Kamal Mostafa ka...@canonical.com
---
drivers/char/virtio_console.c | 13 ++---
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3e338a7..ff015e7 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -278,9 +278,12 @@ static struct port *find_port_by_devt_in_portdev(struct
ports_device *portdev,
unsigned long flags;
spin_lock_irqsave(portdev-ports_lock, flags);
- list_for_each_entry(port, portdev-ports, list)
- if (port-cdev-dev == dev)
+ list_for_each_entry(port, portdev-ports, list) {
+ if (port-cdev-dev == dev) {
+ kref_get(port-kref);
goto out;
+ }
+ }
port = NULL;
out:
spin_unlock_irqrestore(portdev-ports_lock, flags);
@@ -1042,14 +1045,10 @@ static int port_fops_open(struct inode *inode, struct
file *filp)
struct port *port;
int ret;
+ /* We get the port with a kref here */
port = find_port_by_devt(cdev-dev);
filp-private_data = port;
- /* Prevent against a port getting hot-unplugged at the same time */
- spin_lock_irq(port-portdev-ports_lock);
- kref_get(port-kref);
- spin_unlock_irq(port-portdev-ports_lock);
-
/*
* Don't allow opening of console port devices -- that's done
* via /dev/hvc
--
1.8.1.2
--
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Please read the FAQ at http://www.tux.org/lkml/
