[PATCH 6.19 749/844] drm/amdkfd: Fix out-of-bounds write in kfd_event_page_set()

[Sasha Levin]

From: Sunday Clement <Sunday.Clement@xxxxxxx>

[ Upstream commit 8a70a26c9f34baea6c3199a9862ddaff4554a96d ]

The kfd_event_page_set() function writes KFD_SIGNAL_EVENT_LIMIT * 8
bytes via memset without checking the buffer size parameter. This allows
unprivileged userspace to trigger an out-of bounds kernel memory write
by passing a small buffer, leading to  potential privilege
escalation.

Signed-off-by: Sunday Clement <Sunday.Clement@xxxxxxx>
Reviewed-by: Alexander Deucher <Alexander.Deucher@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/amdkfd/kfd_events.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
index 5a190dd6be4e2..844a6a28a6408 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
@@ -331,6 +331,12 @@ static int kfd_event_page_set(struct kfd_process *p, void *kernel_address,
 	if (p->signal_page)
 		return -EBUSY;
 
+	if (size < KFD_SIGNAL_EVENT_LIMIT * 8) {
+		pr_err("Event page size %llu is too small, need at least %lu bytes\n",
+				size, (unsigned long)(KFD_SIGNAL_EVENT_LIMIT * 8));
+		return -EINVAL;
+	}
+
 	page = kzalloc(sizeof(*page), GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;
-- 
2.51.0