2011-05-19 19:41:46

by Armando Visconti

[permalink] [raw]

Subject: [PATCH] HID: Fixed a crash in hid_report_raw_event() function.

---

I'm using a Data Modul EasyTouch USB multitouch controller,
which is issuing a hid report with a size equals to 0. The rsize
value gets set to 536870912 and Linux is crashing in the memset
because the value is too big.

Signed-off-by: Armando Visconti <[email protected]>
---
drivers/hid/hid-core.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index c3d6626..3e972e3 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1045,6 +1045,9 @@ void hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,

rsize = ((report->size - 1) >> 3) + 1;

+ if (rsize > HID_MAX_BUFFER_SIZE)
+ rsize = HID_MAX_BUFFER_SIZE;
+
if (csize < rsize) {
dbg_hid("report %d is too short, (%d < %d)\n", report->id,
csize, rsize);
--
1.7.4

2011-05-20 08:26:40

by Jiri Kosina

[permalink] [raw]

Subject: Re: [PATCH] HID: Fixed a crash in hid_report_raw_event() function.

---

On Thu, 19 May 2011, Armando Visconti wrote:

> I'm using a Data Modul EasyTouch USB multitouch controller,
> which is issuing a hid report with a size equals to 0. The rsize
> value gets set to 536870912 and Linux is crashing in the memset
> because the value is too big.
>
> Signed-off-by: Armando Visconti <[email protected]>
> ---
> drivers/hid/hid-core.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index c3d6626..3e972e3 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1045,6 +1045,9 @@ void hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
>
> rsize = ((report->size - 1) >> 3) + 1;
>
> + if (rsize > HID_MAX_BUFFER_SIZE)
> + rsize = HID_MAX_BUFFER_SIZE;
> +
> if (csize < rsize) {
> dbg_hid("report %d is too short, (%d < %d)\n", report->id,
> csize, rsize);

Applied, thank you.

--
Jiri Kosina
SUSE Labs

2011-05-20 16:02:14

by Valdis Klētnieks

[permalink] [raw]

Subject: Re: [PATCH] HID: Fixed a crash in hid_report_raw_event() function.

---

On Thu, 19 May 2011 21:41:22 +0200, Armando Visconti said:
> I'm using a Data Modul EasyTouch USB multitouch controller,
> which is issuing a hid report with a size equals to 0. The rsize
> value gets set to 536870912 and Linux is crashing in the memset
> because the value is too big.
>
> Signed-off-by: Armando Visconti <[email protected]>
> ---
> drivers/hid/hid-core.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index c3d6626..3e972e3 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1045,6 +1045,9 @@ void hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
>
> rsize = ((report->size - 1) >> 3) + 1;
>
> + if (rsize > HID_MAX_BUFFER_SIZE)
> + rsize = HID_MAX_BUFFER_SIZE;
> +
> if (csize < rsize) {
> dbg_hid("report %d is too short, (%d < %d)\n", report->id,
> csize, rsize);

I'm thinking this is papering over the bug, and causing us to process a max-sized
buffer when the other end gave *zero* bytes back - this can't be good.

Probably should be more like this:

if (!report->size) then /*
rsize = MIN_VALID_SIZE; /* whatever it should be here */
else {
rsize = ((report->size - 1) >> 3) + 1;
if (rsize > HID_MAX_BUFFER_SIZE)
rsize = HID_MAX_BUFFER_SIZE;
}

if (csize < rsize) {


That last if() still looks squirrely - if we have an effectively zero rsize,
the report is short and the dbg_hid should fire. Did we want "csize > rsize"
instead?

---

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