Re: [PATCH] Input: i8042: add a check in i8042_interrupt
From: "dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>
Date: 2017-07-02 22:27:44
Also in:
lkml
Subsystem:
input (keyboard, mouse, joystick, touchscreen) drivers, the rest · Maintainers:
Dmitry Torokhov, Linus Torvalds
Hi, On Sat, Jun 24, 2017 at 09:38:48AM +0000, chenhong (N) wrote:
Description of problem:
Encounterd BUG case:
serio: i8042 KBD port at 0x60,0x64 irq 1
BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
IP: [<ffffffff8150feaf>] _spin_lock_irqsave+0x1f/0x40
PGD 0
Oops: 0002 [#1] SMP
last sysfs file:
CPU 0
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.32-358.el6.x86_64 #1 QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:[<ffffffff8150feaf>] [<ffffffff8150feaf>] _spin_lock_irqsave+0x1f/0x40
RSP: 0018:ffff880028203cc0 EFLAGS: 00010082
RAX: 0000000000010000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000282 RSI: 0000000000000098 RDI: 0000000000000050
RBP: ffff880028203cc0 R08: ffff88013e79c000 R09: ffff880028203ee0
R10: 0000000000000298 R11: 0000000000000282 R12: 0000000000000050
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000098
FS: 0000000000000000(0000) GS:ffff880028200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 0000000000000050 CR3: 0000000001a85000 CR4: 00000000001407f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 1, threadinfo ffff88013e79c000, task ffff88013e79b500)
Stack:
ffff880028203d00 ffffffff813de186 ffffffffffffff02 0000000000000000
<d> 0000000000000000 0000000000000000 0000000000000000 0000000000000098
<d> ffff880028203d70 ffffffff813e0162 ffff880028203d20 ffffffff8103b8ac
Call Trace:
<IRQ>
[<ffffffff813de186>] serio_interrupt+0x36/0xa0
[<ffffffff813e0162>] i8042_interrupt+0x132/0x3a0
[<ffffffff8103b8ac>] ? kvm_clock_read+0x1c/0x20
[<ffffffff8103b8b9>] ? kvm_clock_get_cycles+0x9/0x10
[<ffffffff810e1640>] handle_IRQ_event+0x60/0x170
[<ffffffff8103b154>] ? kvm_guest_apic_eoi_write+0x44/0x50
[<ffffffff810e3d8e>] handle_edge_irq+0xde/0x180
[<ffffffff8100de89>] handle_irq+0x49/0xa0
[<ffffffff81516c8c>] do_IRQ+0x6c/0xf0
[<ffffffff8100b9d3>] ret_from_intr+0x0/0x11
[<ffffffff81076f63>] ? __do_softirq+0x73/0x1e0
[<ffffffff8109b75b>] ? hrtimer_interrupt+0x14b/0x260
[<ffffffff8100c1cc>] ? call_softirq+0x1c/0x30
[<ffffffff8100de05>] ? do_softirq+0x65/0xa0
[<ffffffff81076d95>] ? irq_exit+0x85/0x90
[<ffffffff81516d80>] ? smp_apic_timer_interrupt+0x70/0x9b
[<ffffffff8100bb93>] ? apic_timer_interrupt+0x13/0x20
Version-Release number of selected component (if applicable):
RELEASE: 2.6.32-358.el6.x86_64 (Red Hat Enterprise Linux 6.4)
VERSION: #1 SMP Thu Feb 21 02:37:52 EST 2013
The problem was also reproduced on Red Hat Enterprise Linux 7.3-x86_64(3.10.0-514.el7)
Cause of the problem:
static irqreturn_t i8042_interrupt(int irq, void *dev_id)
{
......
serio = port->exists ? port->serio : NULL;
......
if (likely(port->exists && !filtered))
serio_interrupt(serio, data, dfl);
......
}
static int i8042_start(struct serio *serio)
{
struct i8042_port *port = serio->port_data;
port->exists = true;
mb();
return 0;
}
i8042_probe
|
i8042_setup_kbd --> request_irq(i8042_interrupt)
|
i8042_register_ports --> serio_queue_event(SERIO_REGISTER_PORT) --> serio_handle_event --> serio_add_port --> i8042_start
i8042_start which set port->exists be true may be called during the i8042_interrupt function according to the analysis of initialization order. If port->exists is set to be true after the assignment of serio and before calling of serio_interrupt, a NULL pointer will be passed to serio_interrupt. The latest upstream kernel still has this problem.Thank you for your report and the correct analysis of the problem.
quoted hunk
Solution for this problem Add a check for serio to prevent NULL pointer.--- a/drivers/input/serio/i8042.c 2017-06-19 16:44:50.890078100 +0800 +++ b/drivers/input/serio/i8042.c 2017-06-19 16:45:20.230022700 +0800@@ -524,7 +524,7 @@ i8042_interruptspin_unlock_irqrestore(&i8042_lock, flags); - if (likely(port->exists && !filtered)) + if (likely(port->exists && !filtered && serio))
I do not think we need to check port->exists here, just checking serio should be enough. Also, please check Documentation/SubmittingPatches when submitting patches in the future. I believe we want the version of the patch below. Thanks! -- Dmitry Input: i8042 - fix crash at boot time From: Dmitry Torokhov <dmitry.torokhov@gmail.com> The driver checks port->exists twice in i8042_interrupt(), first when trying to assign temporary "serio" variable, and second time when deciding whether it should call serio_interrupt(). The value of port->exists may change between the 2 checks, and we may end up calling serio_interrupt() with a NULL pointer: BUG: unable to handle kernel NULL pointer dereference at 0000000000000050 IP: [<ffffffff8150feaf>] _spin_lock_irqsave+0x1f/0x40 PGD 0 Oops: 0002 [#1] SMP last sysfs file: CPU 0 Modules linked in: Pid: 1, comm: swapper Not tainted 2.6.32-358.el6.x86_64 #1 QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:[<ffffffff8150feaf>] [<ffffffff8150feaf>] _spin_lock_irqsave+0x1f/0x40 RSP: 0018:ffff880028203cc0 EFLAGS: 00010082 RAX: 0000000000010000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000282 RSI: 0000000000000098 RDI: 0000000000000050 RBP: ffff880028203cc0 R08: ffff88013e79c000 R09: ffff880028203ee0 R10: 0000000000000298 R11: 0000000000000282 R12: 0000000000000050 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000098 FS: 0000000000000000(0000) GS:ffff880028200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: 0000000000000050 CR3: 0000000001a85000 CR4: 00000000001407f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 1, threadinfo ffff88013e79c000, task ffff88013e79b500) Stack: ffff880028203d00 ffffffff813de186 ffffffffffffff02 0000000000000000 <d> 0000000000000000 0000000000000000 0000000000000000 0000000000000098 <d> ffff880028203d70 ffffffff813e0162 ffff880028203d20 ffffffff8103b8ac Call Trace: <IRQ> [<ffffffff813de186>] serio_interrupt+0x36/0xa0 [<ffffffff813e0162>] i8042_interrupt+0x132/0x3a0 [<ffffffff8103b8ac>] ? kvm_clock_read+0x1c/0x20 [<ffffffff8103b8b9>] ? kvm_clock_get_cycles+0x9/0x10 [<ffffffff810e1640>] handle_IRQ_event+0x60/0x170 [<ffffffff8103b154>] ? kvm_guest_apic_eoi_write+0x44/0x50 [<ffffffff810e3d8e>] handle_edge_irq+0xde/0x180 [<ffffffff8100de89>] handle_irq+0x49/0xa0 [<ffffffff81516c8c>] do_IRQ+0x6c/0xf0 [<ffffffff8100b9d3>] ret_from_intr+0x0/0x11 [<ffffffff81076f63>] ? __do_softirq+0x73/0x1e0 [<ffffffff8109b75b>] ? hrtimer_interrupt+0x14b/0x260 [<ffffffff8100c1cc>] ? call_softirq+0x1c/0x30 [<ffffffff8100de05>] ? do_softirq+0x65/0xa0 [<ffffffff81076d95>] ? irq_exit+0x85/0x90 [<ffffffff81516d80>] ? smp_apic_timer_interrupt+0x70/0x9b [<ffffffff8100bb93>] ? apic_timer_interrupt+0x13/0x20 To avoid the issue let's change the second check to test whether serio is NULL or not. Also, let's take i8042_lock in i8042_start() and i8042_stop() instead of trying to be overly smart and using memory barriers and synchronize_irq(). Reported-by: Chen Hong <redacted> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/input/serio/i8042.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index c52da651269b..2f19bdbf64b5 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c@@ -436,8 +436,10 @@ static int i8042_start(struct serio *serio) { struct i8042_port *port = serio->port_data; + spin_lock_irq(&i8042_lock); port->exists = true; - mb(); + spin_unlock_irq(&i8042_lock); + return 0; }
@@ -450,16 +452,10 @@ static void i8042_stop(struct serio *serio) { struct i8042_port *port = serio->port_data; + spin_lock_irq(&i8042_lock); port->exists = false; - - /* - * We synchronize with both AUX and KBD IRQs because there is - * a (very unlikely) chance that AUX IRQ is raised for KBD port - * and vice versa. - */ - synchronize_irq(I8042_AUX_IRQ); - synchronize_irq(I8042_KBD_IRQ); port->serio = NULL; + spin_unlock_irq(&i8042_lock); } /*
@@ -576,7 +572,7 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id) spin_unlock_irqrestore(&i8042_lock, flags); - if (likely(port->exists && !filtered)) + if (likely(serio && !filtered)) serio_interrupt(serio, data, dfl); out: