Messages in this thread | | | Subject | Re: [PATCH] gpu: ttm: fix GPF in ttm_bo_release | From | Christian König <> | Date | Thu, 8 Jul 2021 08:49:48 +0200 |
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Am 07.07.21 um 20:51 schrieb Pavel Skripkin: > My local syzbot instance hit GPF in ttm_bo_release(). > Unfortunately, syzbot didn't produce a reproducer for this, but I > found out possible scenario: > > drm_gem_vram_create() <-- drm_gem_vram_object kzalloced > (bo embedded in this object) > ttm_bo_init() > ttm_bo_init_reserved() > ttm_resource_alloc() > man->func->alloc() <-- allocation failure > ttm_bo_put() > ttm_bo_release() > ttm_mem_io_free() <-- bo->resource == NULL passed > as second argument > *GPF* > > So, I've added check in ttm_bo_release() to avoid passing > NULL as second argument to ttm_mem_io_free().
There is another ocassion of this a bit down before we call ttm_bo_move_to_lru_tail() apart from that good catch.
But I'm wondering if we should make the functions NULL save instead of the external check.
Thanks, Christian.
> > Fail log: > > KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] > CPU: 1 PID: 10419 Comm: syz-executor.3 Not tainted 5.13.0-rc7-next-20210625 #7 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 > RIP: 0010:ttm_mem_io_free+0x28/0x170 drivers/gpu/drm/ttm/ttm_bo_util.c:66 > Code: b1 90 41 56 41 55 41 54 55 48 89 fd 53 48 89 f3 e8 cd 19 24 fd 4c 8d 6b 20 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 2a 01 00 00 4c 8b 63 20 31 ff 4c 89 e6 e8 00 1f > RSP: 0018:ffffc900141df968 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90010da0000 > RDX: 0000000000000004 RSI: ffffffff84513ea3 RDI: ffff888041fbc010 > RBP: ffff888041fbc010 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000020 R14: ffff88806b258800 R15: ffff88806b258a38 > FS: 00007fa6e9845640(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fad61265e18 CR3: 000000005ad79000 CR4: 0000000000350ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > ttm_bo_release+0xd94/0x10a0 drivers/gpu/drm/ttm/ttm_bo.c:422 > kref_put include/linux/kref.h:65 [inline] > ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:470 [inline] > ttm_bo_init_reserved+0x7cb/0x960 drivers/gpu/drm/ttm/ttm_bo.c:1050 > ttm_bo_init+0x105/0x270 drivers/gpu/drm/ttm/ttm_bo.c:1074 > drm_gem_vram_create+0x332/0x4c0 drivers/gpu/drm/drm_gem_vram_helper.c:228 > > Fixes: d3116756a710 ("drm/ttm: rename bo->mem and make it a pointer") > Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> > --- > drivers/gpu/drm/ttm/ttm_bo.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c > index 1b950b45cf4b..15eb97459eab 100644 > --- a/drivers/gpu/drm/ttm/ttm_bo.c > +++ b/drivers/gpu/drm/ttm/ttm_bo.c > @@ -419,7 +419,8 @@ static void ttm_bo_release(struct kref *kref) > bo->bdev->funcs->release_notify(bo); > > drm_vma_offset_remove(bdev->vma_manager, &bo->base.vma_node); > - ttm_mem_io_free(bdev, bo->resource); > + if (bo->resource) > + ttm_mem_io_free(bdev, bo->resource); > } > > if (!dma_resv_test_signaled(bo->base.resv, true) ||
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