Commit d9ec75d0 authored Apr 17, 2019 by Alexander Shishkin Committed by Greg Kroah-Hartman May 25, 2019

stm class: Fix channel bitmap on 32-bit systems

commit 51e0f227812ed81a368de54157ebe14396b4be03 upstream.

Commit 7bd1d409 ("stm class: Introduce an abstraction for System Trace
Module devices") naively calculates the channel bitmap size in 64-bit
chunks regardless of the size of underlying unsigned long, making the
bitmap half as big on a 32-bit system. This leads to an out of bounds
access with the upper half of the bitmap.

Fix this by using BITS_TO_LONGS. While at it, convert to using
struct_size() for the total size calculation of the master struct.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Fixes: 7bd1d409 ("stm class: Introduce an abstraction for System Trace Module devices")
Reported-by: Mulu He <muluhe@codeaurora.org>
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 44bc4e88

drivers/hwtracing/stm/core.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -166,11 +166,10 @@ stm_master(struct stm_device *stm, unsigned int idx)
		static int stp_master_alloc(struct stm_device *stm, unsigned int idx)
		{
		struct stp_master *master;
		size_t size;

		size = ALIGN(stm->data->sw_nchannels, 8) / 8;
		size += sizeof(struct stp_master);
		master = kzalloc(size, GFP_ATOMIC);
		master = kzalloc(struct_size(master, chan_map,
		BITS_TO_LONGS(stm->data->sw_nchannels)),
		GFP_ATOMIC);
		if (!master)
		return -ENOMEM;