From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [v1,1/1] USB: serial: Add boundry check for read_urbs array access From: Greg Kroah-Hartman Message-Id: <20180307205840.GA6242@kroah.com> Date: Wed, 7 Mar 2018 12:58:40 -0800 To: sathyanarayanan.kuppuswamy@linux.intel.com Cc: johan@kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org List-ID: T24gV2VkLCBNYXIgMDcsIDIwMTggYXQgMTI6MjM6NTZQTSAtMDgwMCwgc2F0aHlhbmFyYXlhbmFu Lmt1cHB1c3dhbXlAbGludXguaW50ZWwuY29tIHdyb3RlOgo+IEZyb206IEt1cHB1c3dhbXkgU2F0 aHlhbmFyYXlhbmFuIDxzYXRoeWFuYXJheWFuYW4ua3VwcHVzd2FteUBsaW51eC5pbnRlbC5jb20+ Cj4gCj4gSW4gdXNiX3NlcmlhbF9nZW5lcmljX3N1Ym1pdF9yZWFkX3VyYigpIGZ1bmN0aW9uIHdl IGFyZSBhY2Nlc3NpbmcgdGhlCj4gcG9ydC0+cmVhZF91cmJzIGFycmF5IHdpdGhvdXQgYW55IGJv dW5kcnkgY2hlY2tzLiBUaGlzIG1pZ2h0IGxlYWQgdG8KPiBrZXJuZWwgcGFuaWMgd2hlbiBpbmRl eCB2YWx1ZSBnb2VzIGFib3ZlIGFycmF5IGxlbmd0aC4KPiAKPiBPbmUgcG9zaWJsZSBjYWxsIHBh dGggZm9yIHRoaXMgaXNzdWUgaXMsCj4gCj4gdXNiX3NlcmlhbF9nZW5lcmljX3JlYWRfYnVsa19j YWxsYmFjaygpCj4gewo+ICAuLi4KPiAgaWYgKCFwb3J0LT50aHJvdHRsZWQpIHsKPiAJdXNiX3Nl cmlhbF9nZW5lcmljX3N1Ym1pdF9yZWFkX3VyYihwb3J0LCBpLCBHRlBfQVRPTUlDKTsKPiAgLi4u Cj4gfQoKSG93IGRvZXMgaSBldmVyIGdldCB0byBiZSBncmVhdGVyIHRoYW4gdGhlIGFycmF5IHNp emUgaGVyZSBpbiB0aGlzCmZ1bmN0aW9uPyAgSXQgZGlyZWN0bHkgY2FtZSBmcm9tIGxvb2tpbmcg aW4gdGhhdCBhcnJheSBpbiB0aGUgZmlyc3QKcGxhY2UgOikKClNvIEkgZG9uJ3Qgc2VlIHdoeSB5 b3VyIGNoZWNrIGlzIG5lZWRlZCwgd2hhdCBvdGhlciBjb2RlIHBhdGggd291bGQgZXZlcgpjYWxs IHRoaXMgZnVuY3Rpb24gaW4gYSB3YXkgdGhhdCB0aGUgYm91bmRzIGNoZWNrIHdvdWxkIGJlIG5l ZWRlZD8KCnRoYW5rcywKCmdyZWcgay1oCi0tLQpUbyB1bnN1YnNjcmliZSBmcm9tIHRoaXMgbGlz dDogc2VuZCB0aGUgbGluZSAidW5zdWJzY3JpYmUgbGludXgtdXNiIiBpbgp0aGUgYm9keSBvZiBh IG1lc3NhZ2UgdG8gbWFqb3Jkb21vQHZnZXIua2VybmVsLm9yZwpNb3JlIG1ham9yZG9tbyBpbmZv IGF0ICBodHRwOi8vdmdlci5rZXJuZWwub3JnL21ham9yZG9tby1pbmZvLmh0bWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 Mar 2018 12:58:40 -0800 From: Greg KH To: sathyanarayanan.kuppuswamy@linux.intel.com Cc: johan@kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 1/1] USB: serial: Add boundry check for read_urbs array access Message-ID: <20180307205840.GA6242@kroah.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Mar 07, 2018 at 12:23:56PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote: > From: Kuppuswamy Sathyanarayanan > > In usb_serial_generic_submit_read_urb() function we are accessing the > port->read_urbs array without any boundry checks. This might lead to > kernel panic when index value goes above array length. > > One posible call path for this issue is, > > usb_serial_generic_read_bulk_callback() > { > ... > if (!port->throttled) { > usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC); > ... > } How does i ever get to be greater than the array size here in this function? It directly came from looking in that array in the first place :) So I don't see why your check is needed, what other code path would ever call this function in a way that the bounds check would be needed? thanks, greg k-h