From: Arnd Bergmann <arnd@arndb.de>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Jiri Kosina <jikos@kernel.org>,
linux-input@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/5] HID: intel_ish-hid: fix potential uninitialized data usage
Date: Wed, 24 May 2017 10:29:26 +0200 [thread overview]
Message-ID: <CAK8P3a3h7P+DdNt3P4EUWE4S8knHuBeVm6N+6svi563ppaHZgw@mail.gmail.com> (raw)
In-Reply-To: <1495578269.14443.4.camel@linux.intel.com>
On Wed, May 24, 2017 at 12:24 AM, Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
> On Thu, 2017-05-18 at 22:21 +0200, Arnd Bergmann wrote:
>> gcc points out an uninialized pointer dereference that could happen
>> if we ever get to recv_ishtp_cl_msg_dma() or recv_ishtp_cl_msg()
>> with an empty &dev->read_list:
> In that case complete_rb should be NULL and it should not go to
>
> if (complete_rb) {
>
> shouldn't enter and cl is not dereferenced.
>
> So not sure why is this warning.
Correct. Unfortunately gcc cannot track this for complex functions, as
figuring this out is a not a solvable problem in general. I think in this
particular case, it gives up either because of the multiple 'goto' and
'continue' statements inside of the loop that get in the way of a full
analysis, or the 'spin_unlock_irqrestore' makes it forget the state.
I've seen both in the past.
However, just like gcc gets confused easily, a human reader trying
to understand the function will have the same issue, so my workaround
also helps there.
Arnd
next prev parent reply other threads:[~2017-05-24 8:33 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-18 20:21 HID: intel_ish-hid: various cleanups Arnd Bergmann
2017-05-18 20:21 ` [PATCH v2 1/5] HID: intel_ish-hid: fix potential uninitialized data usage Arnd Bergmann
2017-05-22 19:17 ` Srinivas Pandruvada
2017-05-22 21:33 ` Arnd Bergmann
2017-05-23 22:24 ` Srinivas Pandruvada
2017-05-24 8:29 ` Arnd Bergmann [this message]
2017-05-26 20:58 ` Srinivas Pandruvada
2017-05-18 20:21 ` [PATCH v2 2/5] HID: intel_ish-hid: clarify locking in client code Arnd Bergmann
2017-05-26 20:58 ` Srinivas Pandruvada
2017-05-18 20:21 ` [PATCH v2 3/5] HID: intel_ish-hid: convert timespec to ktime_t Arnd Bergmann
2017-05-26 20:58 ` Srinivas Pandruvada
2017-05-18 20:21 ` [PATCH v2 4/5] HID: intel_ish-hid: fix format string for size_t Arnd Bergmann
2017-05-22 23:46 ` Srinivas Pandruvada
2017-05-23 8:35 ` Arnd Bergmann
2017-05-26 20:58 ` Srinivas Pandruvada
2017-05-18 20:21 ` [PATCH v2 5/5] HID: intel_ish-hid: enable compile testing Arnd Bergmann
2017-05-26 20:59 ` Srinivas Pandruvada
2017-05-26 20:57 ` HID: intel_ish-hid: various cleanups Srinivas Pandruvada
2017-05-30 12:13 ` Jiri Kosina
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