Commit 7bd1d4093c2f ("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: 7bd1d4093c2f ("stm class: Introduce an abstraction for System Trace Module devices") Reported-by: Mulu He muluhe@codeaurora.org Cc: stable@vger.kernel.org # v4.4+ --- drivers/hwtracing/stm/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index 5b5807cbcf7c..e55b902560de 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -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;