Re: [PATCH v2 1/5] HID: intel_ish-hid: fix potential uninitialized data usage
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date: 2017-05-23 22:24:41
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lkml
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
quoted hunk ↗ jump to hunk
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.cb/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);