This patch has been merged to Linus tree. The upstream commit ID is 37309f47e2f5.

The issue was introduced by 83417206427b ("HID: wacom: Queue events with missing type/serial data for later processing"). I forgot to cc stable.

Let me know if you have questions, Ping

---------- Forwarded message --------- From: Ping Cheng pinglinux@gmail.com Date: Wed, Dec 9, 2020 at 8:52 PM Subject: [PATCH] HID: wacom: Fix memory leakage caused by kfifo_alloc To: linux-input@vger.kernel.org, syzbot+5b49c9695968d7250a26@syzkaller.appspotmail.com Cc: jkosina@suse.cz, benjamin.tissoires@gmail.com, Ping Cheng ping.cheng@wacom.com

As reported by syzbot below, kfifo_alloc'd memory would not be freed if a non-zero return value is triggered in wacom_probe. This patch creates and uses devm_kfifo_alloc to allocate and free itself.

BUG: memory leak unreferenced object 0xffff88810dc44a00 (size 512): comm "kworker/1:2", pid 3674, jiffies 4294943617 (age 14.100s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<0000000023e1afac>] kmalloc_array include/linux/slab.h:592 [inline] [<0000000023e1afac>] __kfifo_alloc+0xad/0x100 lib/kfifo.c:43 [<00000000c477f737>] wacom_probe+0x1a1/0x3b0 drivers/hid/wacom_sys.c:2727 [<00000000b3109aca>] hid_device_probe+0x16b/0x210 drivers/hid/hid-core.c:2281 [<00000000aff7c640>] really_probe+0x159/0x480 drivers/base/dd.c:554 [<00000000778d0bc3>] driver_probe_device+0x84/0x100 drivers/base/dd.c:738 [<000000005108dbb5>] __device_attach_driver+0xee/0x110 drivers/base/dd.c:844 [<00000000efb7c59e>] bus_for_each_drv+0xb7/0x100 drivers/base/bus.c:431 [<0000000024ab1590>] __device_attach+0x122/0x250 drivers/base/dd.c:912 [<000000004c7ac048>] bus_probe_device+0xc6/0xe0 drivers/base/bus.c:491 [<00000000b93050a3>] device_add+0x5ac/0xc30 drivers/base/core.c:2936 [<00000000e5b46ea5>] hid_add_device+0x151/0x390 drivers/hid/hid-core.c:2437 [<00000000c6add147>] usbhid_probe+0x412/0x560 drivers/hid/usbhid/hid-core.c:1407 [<00000000c33acdb4>] usb_probe_interface+0x177/0x370 drivers/usb/core/driver.c:396 [<00000000aff7c640>] really_probe+0x159/0x480 drivers/base/dd.c:554 [<00000000778d0bc3>] driver_probe_device+0x84/0x100 drivers/base/dd.c:738 [<000000005108dbb5>] __device_attach_driver+0xee/0x110 drivers/base/dd.c:844

https://syzkaller.appspot.com/bug?extid=5b49c9695968d7250a26

Reported-by: syzbot+5b49c9695968d7250a26@syzkaller.appspotmail.com Signed-off-by: Ping Cheng ping.cheng@wacom.com Reviewed-by: Benjamin Tissoires benjamin.tissoires@redhat.com --- drivers/hid/wacom_sys.c | 35 ++++++++++++++++++++++++++++++++--- 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c index cd71e7133944..9e852b4bbf92 100644 --- a/drivers/hid/wacom_sys.c +++ b/drivers/hid/wacom_sys.c @@ -1270,6 +1270,37 @@ static int wacom_devm_sysfs_create_group(struct wacom *wacom, group); }

+static void wacom_devm_kfifo_release(struct device *dev, void *res) +{ + struct kfifo_rec_ptr_2 *devres = res; + + kfifo_free(devres); +} + +static int wacom_devm_kfifo_alloc(struct wacom *wacom) +{ + struct wacom_wac *wacom_wac = &wacom->wacom_wac; + struct kfifo_rec_ptr_2 *pen_fifo = &wacom_wac->pen_fifo; + int error; + + pen_fifo = devres_alloc(wacom_devm_kfifo_release, + sizeof(struct kfifo_rec_ptr_2), + GFP_KERNEL); + + if (!pen_fifo) + return -ENOMEM; + + error = kfifo_alloc(pen_fifo, WACOM_PKGLEN_MAX, GFP_KERNEL); + if (error) { + devres_free(pen_fifo); + return error; + } + + devres_add(&wacom->hdev->dev, pen_fifo); + + return 0; +} + enum led_brightness wacom_leds_brightness_get(struct wacom_led *led) { struct wacom *wacom = led->wacom; @@ -2724,7 +2755,7 @@ static int wacom_probe(struct hid_device *hdev, if (features->check_for_hid_type && features->hid_type != hdev->type) return -ENODEV;

- error = kfifo_alloc(&wacom_wac->pen_fifo, WACOM_PKGLEN_MAX, GFP_KERNEL); + error = wacom_devm_kfifo_alloc(wacom); if (error) return error;

@@ -2786,8 +2817,6 @@ static void wacom_remove(struct hid_device *hdev)

if (wacom->wacom_wac.features.type != REMOTE) wacom_release_resources(wacom); - - kfifo_free(&wacom_wac->pen_fifo); }

#ifdef CONFIG_PM -- 2.17.1