[PATCH 5.5 008/399] drm/dp_mst: fix multiple frees of tx->bytes

Greg Kroah-Hartman
2020-02-21T07:44:54Z

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 2c8bc91488fc57438c43b3bb19deb7fdbc1e5119 ]

Currently tx->bytes is being freed r->num_transactions number of
times because tx is not being set correctly. Fix this by setting
tx to &r->transactions[i] so that the correct objects are being
freed on each loop iteration.

Addresses-Coverity: ("Double free")
Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing + selftests")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120173509.347490-1-colin.king@canonical.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 6cd90cb4b6b10..4a65ef8d8bff3 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -517,8 +517,10 @@ drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
}

if (failed) {
- for (i = 0; i < r->num_transactions; i++)
+ for (i = 0; i < r->num_transactions; i++) {
+ tx = &r->transactions[i];
kfree(tx->bytes);
+ }
return -ENOMEM;
}

--
2.20.1