From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Arnd Bergmann <arnd@arndb.de>, Jiri Kosina <jikos@kernel.org>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/5] HID: intel_ish-hid: fix potential uninitialized data usage
Date: Tue, 23 May 2017 15:24:29 -0700 [thread overview]
Message-ID: <1495578269.14443.4.camel@linux.intel.com> (raw)
In-Reply-To: <20170518202144.3482304-2-arnd@arndb.de>
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.
Thanks,
Srinivas
>
> drivers/hid/intel-ish-hid/ishtp/client.c: In function
> 'recv_ishtp_cl_msg_dma':
> drivers/hid/intel-ish-hid/ishtp/client.c:1049:3: error: 'cl' may be
> used uninitialized in this function [-Werror=maybe-uninitialized]
>
> The warning only appeared in very few randconfig builds, as the
> spinlocks tend to prevent gcc from tracing the variables. I only
> saw it in configurations that had neither SMP nor LOCKDEP enabled.
>
> As we can see, we only enter the case if 'complete_rb' is non-NULL,
> and then 'cl' is known to point to complete_rb->cl. Adding another
> initialization to the same pointer is harmless here and makes it
> clear to the compiler that the behavior is well-defined.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/hid/intel-ish-hid/ishtp/client.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/hid/intel-ish-hid/ishtp/client.c
> b/drivers/hid/intel-ish-hid/ishtp/client.c
> index aad61328f282..78d393e616a4 100644
> --- a/drivers/hid/intel-ish-hid/ishtp/client.c
> +++ b/drivers/hid/intel-ish-hid/ishtp/client.c
> @@ -925,6 +925,7 @@ void recv_ishtp_cl_msg(struct ishtp_device *dev,
> }
>
> if (complete_rb) {
> + cl = complete_rb->cl;
> getnstimeofday(&cl->ts_rx);
> ++cl->recv_msg_cnt_ipc;
> ishtp_cl_read_complete(complete_rb);
> @@ -1045,6 +1046,7 @@ void recv_ishtp_cl_msg_dma(struct ishtp_device
> *dev, void *msg,
> }
>
> if (complete_rb) {
> + cl = complete_rb->cl;
> getnstimeofday(&cl->ts_rx);
> ++cl->recv_msg_cnt_dma;
> ishtp_cl_read_complete(complete_rb);
next prev parent reply other threads:[~2017-05-23 22:24 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 [this message]
2017-05-24 8:29 ` Arnd Bergmann
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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