From 9377de4cb3e8fb6c494fa2f5ae2c3780d3e73822 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Thomas=20Hellstr=C3=B6m?= Date: Thu, 8 Feb 2024 14:21:15 +0100 Subject: [PATCH] drm/xe/vm: Avoid reserving zero fences MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The function xe_vm_prepare_vma was blindly accepting zero as the number of fences and forwarded that to drm_exec_prepare_obj. However, that leads to an out-of-bounds shift in the dma_resv_reserve_fences() and while one could argue that the dma_resv code should be robust against that, avoid attempting to reserve zero fences. Relevant stack trace: [773.183188] ------------[ cut here ]------------ [773.183199] UBSAN: shift-out-of-bounds in ../include/linux/log2.h:57:13 [773.183241] shift exponent 64 is too large for 64-bit type 'long unsigned int' [773.183254] CPU: 2 PID: 1816 Comm: xe_evict Tainted: G U 6.8.0-rc3-xe #1 [773.183256] Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 2014 10/14/2022 [773.183257] Call Trace: [773.183258] [773.183260] dump_stack_lvl+0xaf/0xd0 [773.183266] dump_stack+0x10/0x20 [773.183283] ubsan_epilogue+0x9/0x40 [773.183286] __ubsan_handle_shift_out_of_bounds+0x10f/0x170 [773.183293] dma_resv_reserve_fences.cold+0x2b/0x48 [773.183295] ? ww_mutex_lock+0x3c/0x110 [773.183301] drm_exec_prepare_obj+0x45/0x60 [drm_exec] [773.183313] xe_vm_prepare_vma+0x33/0x70 [xe] [773.183375] xe_vma_destroy_unlocked+0x55/0xa0 [xe] [773.183427] xe_vm_close_and_put+0x526/0x940 [xe] Fixes: 2714d5093620 ("drm/xe: Convert pagefaulting code to use drm_exec") Cc: Thomas Hellström Cc: Matthew Brost Cc: Rodrigo Vivi Signed-off-by: Thomas Hellström Reviewed-by: Matthew Auld Link: https://patchwork.freedesktop.org/patch/msgid/20240208132115.3132-1-thomas.hellstrom@linux.intel.com (cherry picked from commit eb538b5574251a449f40b1ee35efc631228c8992) Signed-off-by: Thomas Hellström --- drivers/gpu/drm/xe/xe_vm.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index 865e10d0a06a..7b00faa67287 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -995,9 +995,16 @@ int xe_vm_prepare_vma(struct drm_exec *exec, struct xe_vma *vma, int err; XE_WARN_ON(!vm); - err = drm_exec_prepare_obj(exec, xe_vm_obj(vm), num_shared); - if (!err && bo && !bo->vm) - err = drm_exec_prepare_obj(exec, &bo->ttm.base, num_shared); + if (num_shared) + err = drm_exec_prepare_obj(exec, xe_vm_obj(vm), num_shared); + else + err = drm_exec_lock_obj(exec, xe_vm_obj(vm)); + if (!err && bo && !bo->vm) { + if (num_shared) + err = drm_exec_prepare_obj(exec, &bo->ttm.base, num_shared); + else + err = drm_exec_lock_obj(exec, &bo->ttm.base); + } return err; } -- 2.20.1