From dc14753664240cedf669623b27ae9922b0618b25 Mon Sep 17 00:00:00 2001 From: Taimuraz Kaitmazov Date: Tue, 18 Aug 2026 02:06:55 +0300 Subject: [PATCH] accel/amdxdna: return early from a zero-length flush SYNC_BO does not constrain its size, so a request for zero bytes reaches drm_clflush_virt_range(), which ends with an unconditional clflushopt(end - 1). For an empty range that is the byte before the mapping, and abo->mem.kva comes from vmap(), so the access lands in the guard page below the vmalloc area and faults: BUG: unable to handle page fault for address: ffffd16fbbc70fff #PF: supervisor read access in kernel mode Oops: Oops: 0000 [#1] SMP NOPTI CPU: 7 UID: 1000 Comm: sync_bo_probe RIP: 0010:drm_clflush_virt_range+0x3c/0x70 Call Trace: amdxdna_drm_sync_bo_ioctl+0x124/0x430 [amdxdna] drm_ioctl+0x301/0x4c0 __x64_sys_ioctl+0x115/0x2f0 do_syscall_64+0xa6/0x3d0 Any process that can open the render node can do this. Reproduced 3 of 3 times on a Strix Point NPU (1022:17f0), by calling SYNC_BO with size 0 on an AMDXDNA_BO_SHARE object. The import arm takes the same request but flushes the whole scatterlist, so it survives it. Nothing needs flushing for an empty range, so answer before choosing a path. Fixes: e252e3f3488a ("accel/amdxdna: Revise device bo creation and free") Cc: stable@vger.kernel.org Signed-off-by: Taimuraz Kaitmazov Reviewed-by: Lizhi Hou Signed-off-by: Lizhi Hou Link: https://patch.msgid.link/20260817230655.356785-1-taimuraz@kaitmazov.com --- drivers/accel/amdxdna/amdxdna_gem.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c index 1c63eff0a4a8..2a16de96e6a4 100644 --- a/drivers/accel/amdxdna/amdxdna_gem.c +++ b/drivers/accel/amdxdna/amdxdna_gem.c @@ -1247,6 +1247,9 @@ static int amdxdna_flush_bo(struct amdxdna_gem_obj *abo, u64 offset, u64 size) return -EINVAL; size = min(abo->mem.size, end) - offset; + if (!size) + return 0; + if (is_import_bo(abo)) drm_clflush_sg(abo->base.sgt); else if (amdxdna_gem_vmap(abo))