From da5e45e619b3f101420c38b3006a9ae4f3ad19b0 Mon Sep 17 00:00:00 2001 From: Māris Nartišs Date: Fri, 16 Mar 2018 11:38:43 +1000 Subject: drm/nouveau/mmu: ALIGN_DOWN correct variable Commit 7110c89bb8852ff8b0f88ce05b332b3fe22bd11e ("mmu: swap out round for ALIGN") replaced two calls to round/rounddown with ALIGN/ALIGN_DOWN, but erroneously applied ALIGN_DOWN to a different variable (addr) and left intended variable (tail) not rounded/ALIGNed. As a result screen corruption, X lockups are observable. An example of kernel log of affected system with NV98 card where it was bisected: nouveau 0000:01:00.0: gr: TRAP_M2MF 00000002 [IN] nouveau 0000:01:00.0: gr: TRAP_M2MF 00320951 400007c0 00000000 04000000 nouveau 0000:01:00.0: gr: 00200000 [] ch 1 [000fbbe000 DRM] subc 4 class 5039 mthd 0100 data 00000000 nouveau 0000:01:00.0: fb: trapped read at 0040000000 on channel 1 [0fbbe000 DRM] engine 00 [PGRAPH] client 03 [DISPATCH] subclient 04 [M2M_IN] reason 00000006 [NULL_DMAOBJ] Fixes bug 105173 ("[MCP79][Regression] Unhandled NULL pointer dereference in nvkm_object_unmap since kernel 4.15") https://bugs.freedesktop.org/show_bug.cgi?id=105173 Fixes: 7110c89bb885 ("mmu: swap out round for ALIGN ") Tested-by: Pierre Moreau Reviewed-by: Pierre Moreau Signed-off-by: Maris Nartiss Signed-off-by: Ben Skeggs Cc: stable@vger.kernel.org # v4.15+ --- drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c index 93946dcee319..1c12e58f44c2 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c @@ -1354,7 +1354,7 @@ nvkm_vmm_get_locked(struct nvkm_vmm *vmm, bool getref, bool mapref, bool sparse, tail = this->addr + this->size; if (vmm->func->page_block && next && next->page != p) - tail = ALIGN_DOWN(addr, vmm->func->page_block); + tail = ALIGN_DOWN(tail, vmm->func->page_block); if (addr <= tail && tail - addr >= size) { rb_erase(&this->tree, &vmm->free); -- cgit v1.2.3-59-g8ed1b