From mboxrd@z Thu Jan 1 00:00:00 1970 From: Valdis.Kletnieks@vt.edu Subject: Re: [PATCH] HID: Fixed a crash in hid_report_raw_event() function. Date: Fri, 20 May 2011 12:02:04 -0400 Message-ID: <11173.1305907324@localhost> References: <1305834082-14888-1-git-send-email-armando.visconti@st.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1305907324_2669P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Your message of "Thu, 19 May 2011 21:41:22 +0200." <1305834082-14888-1-git-send-email-armando.visconti@st.com> Sender: linux-kernel-owner@vger.kernel.org To: Armando Visconti Cc: jkosina@suse.cz, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-input@vger.kernel.org --==_Exmh_1305907324_2669P Content-Type: text/plain; charset=us-ascii 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 > --- > 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? --==_Exmh_1305907324_2669P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFN1pB8cC3lWbTT17ARArqCAKCQWd9lr6+pYPGwFS/gBUyvELvLPgCfRoi3 iB+t44ebO5hAkXs65hSK+Gs= =drIg -----END PGP SIGNATURE----- --==_Exmh_1305907324_2669P--