From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	William Palacek <William.Palacek@amd.com>,
	Alysa Liu <Alysa.Liu@amd.com>,
	Alex Deucher <alexander.deucher@amd.com>
Subject: [PATCH 6.18 327/396] drm/amdkfd: fix uint32_t overflow in EOP ring buffer size alignment
Date: Fri,  7 Aug 2026 16:38:07 +0200
Message-ID: <20260807143431.346124865@linuxfoundation.org>
In-Reply-To: <20260807143424.272339768@linuxfoundation.org>
References: <20260807143424.272339768@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: William Palacek <William.Palacek@amd.com>

commit 83463a96ea3c7d8ae636a4d6a0ba63c9ce410724 upstream.

eop_ring_buffer_size in struct queue_properties is a u32. In
kfd_queue_acquire_buffers() the expected EOP buffer size is computed as
ALIGN(eop_ring_buffer_size, PAGE_SIZE); ALIGN uses typeof(x), so the
addition is done in 32-bit. A user-supplied size of 0xFFFFF001 wraps to
0, causing kfd_queue_buffer_get() to skip its exact-size check (gated on
size != 0) and accept any BO mapped at the address. On GFX8/GFX9 the MQD
cp_hqd_eop_control is then programmed for an 8KB EOP ring backed by a 4KB
BO, so CP EOP writes can land past the buffer and fault the GPU.

Cast the operand to u64 so the alignment is computed in 64-bit; the size
check in kfd_queue_buffer_get() then rejects the oversized request.

Fixes: 42ea9cf2f16b ("drm/amdkfd: Relax size checking during queue buffer get")
Signed-off-by: William Palacek <William.Palacek@amd.com>
Reviewed-by: Alysa Liu <Alysa.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit ae443117b742c357bfef3a7bddabf76fcf86e9ef)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/amd/amdkfd/kfd_queue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/amdkfd/kfd_queue.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_queue.c
@@ -285,7 +285,7 @@ int kfd_queue_acquire_buffers(struct kfd
 		}
 		err = kfd_queue_buffer_get(vm, (void *)properties->eop_ring_buffer_address,
 					   &properties->eop_buf_bo,
-					   ALIGN(properties->eop_ring_buffer_size, PAGE_SIZE));
+					   ALIGN((u64)properties->eop_ring_buffer_size, PAGE_SIZE));
 		if (err)
 			goto out_err_unreserve;
 	}