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Subject[34-longterm 102/209] HID: hidraw, fix a NULL pointer dereference in hidraw_ioctl
Date
From: Antonio Ospite <ospite@studenti.unina.it>

=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================

commit d20d5ffab92f00188f360c44c791a5ffb988247c upstream.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa02c66b4>] hidraw_ioctl+0xfc/0x32c [hid]
[...]

This is reproducible by disconnecting the device while userspace does
ioctl in a loop and doesn't check return values in order to exit the
loop.

[PG: slightly/trivially reworked for backport to 34]

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/hid/hidraw.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 6eadf1a..0db1a0f 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -243,6 +243,11 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,
void __user *user_arg = (void __user*) arg;

lock_kernel();
+ if (!dev) {
+ ret = -ENODEV;
+ goto out;
+ }
+
switch (cmd) {
case HIDIOCGRDESCSIZE:
if (put_user(dev->hid->rsize, (int __user *)arg))
@@ -315,6 +320,7 @@ static long hidraw_ioctl(struct file *file, unsigned int cmd,

ret = -ENOTTY;
}
+out:
unlock_kernel();
return ret;
}
--
1.7.4.4


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