From 218c1f76b8b25d6dc9d01443f071cb618e206b0c Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Tue, 29 Sep 2015 15:54:58 -0700
Subject: [PATCH] Input: psmouse - fix data race in __ps2_command
The data race happens on ps2dev->cmdcnt and ps2dev->cmdbuf contents.
__ps2_command reads that data concurrently with the interrupt handler. As
the result, for example, if a response arrives just after the timeout,
__ps2_command can copy out garbage from ps2dev->cmdbuf but then see that
ps2dev->cmdcnt is 0 and return success.
Stop the interrupt handler with serio_pause_rx() before reading the
results.
The data race was found with KernelThreadSanitizer (KTSAN).
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/input/serio/libps2.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 75516996db2070..316f2c8971011d 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -212,12 +212,17 @@ int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
* time before the ACK arrives.
*/
if (ps2_sendbyte(ps2dev, command & 0xff,
- command == PS2_CMD_RESET_BAT ? 1000 : 200))
- goto out;
+ command == PS2_CMD_RESET_BAT ? 1000 : 200)) {
+ serio_pause_rx(ps2dev->serio);
+ goto out_reset_flags;
+ }
- for (i = 0; i < send; i++)
- if (ps2_sendbyte(ps2dev, param[i], 200))
- goto out;
+ for (i = 0; i < send; i++) {
+ if (ps2_sendbyte(ps2dev, param[i], 200)) {
+ serio_pause_rx(ps2dev->serio);
+ goto out_reset_flags;
+ }
+ }
/*
* The reset command takes a long time to execute.
@@ -234,17 +239,18 @@ int __ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
!(ps2dev->flags & PS2_FLAG_CMD), timeout);
}
+ serio_pause_rx(ps2dev->serio);
+
if (param)
for (i = 0; i < receive; i++)
param[i] = ps2dev->cmdbuf[(receive - 1) - i];
if (ps2dev->cmdcnt && (command != PS2_CMD_RESET_BAT || ps2dev->cmdcnt != 1))
- goto out;
+ goto out_reset_flags;
rc = 0;
- out:
- serio_pause_rx(ps2dev->serio);
+ out_reset_flags:
ps2dev->flags = 0;
serio_continue_rx(ps2dev->serio);
--
GitLab