[PATCH 5.1 034/122] stm class: Fix channel bitmap on 32-bit systems

Greg Kroah-Hartman
2019-05-23T19:35:07Z

From: Alexander Shishkin <alexander.shishkin@linux.intel.com>

commit 51e0f227812ed81a368de54157ebe14396b4be03 upstream.

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+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hwtracing/stm/core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -166,11 +166,10 @@ stm_master(struct stm_device *stm, unsig
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;