From: Xiaomeng Tong xiam0nd.tong@gmail.com
commit 6ce4431c7ba7954c4fa6a96ce16ca1b2943e1a83 upstream.
The bug is here: return encoder;
The list iterator value 'encoder' will *always* be set and non-NULL by drm_for_each_encoder_mask(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element found. Otherwise it will bypass some NULL checks and lead to invalid memory access passing the check.
To fix this bug, just return 'encoder' when found, otherwise return NULL.
Cc: stable@vger.kernel.org Fixes: 12885ecbfe62d ("drm/nouveau/kms/nvd9-: Add CRC support") Signed-off-by: Xiaomeng Tong xiam0nd.tong@gmail.com Reviewed-by: Lyude Paul lyude@redhat.com [Changed commit title] Signed-off-by: Lyude Paul lyude@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20220327073925.11121-1-xiam0nd... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/nouveau/dispnv50/atom.h | 6 +++--- drivers/gpu/drm/nouveau/dispnv50/crc.c | 27 ++++++++++++++++++++++----- 2 files changed, 25 insertions(+), 8 deletions(-)
--- a/drivers/gpu/drm/nouveau/dispnv50/atom.h +++ b/drivers/gpu/drm/nouveau/dispnv50/atom.h @@ -160,14 +160,14 @@ nv50_head_atom_get(struct drm_atomic_sta static inline struct drm_encoder * nv50_head_atom_get_encoder(struct nv50_head_atom *atom) { - struct drm_encoder *encoder = NULL; + struct drm_encoder *encoder;
/* We only ever have a single encoder */ drm_for_each_encoder_mask(encoder, atom->state.crtc->dev, atom->state.encoder_mask) - break; + return encoder;
- return encoder; + return NULL; }
#define nv50_wndw_atom(p) container_of((p), struct nv50_wndw_atom, state) --- a/drivers/gpu/drm/nouveau/dispnv50/crc.c +++ b/drivers/gpu/drm/nouveau/dispnv50/crc.c @@ -390,9 +390,18 @@ void nv50_crc_atomic_check_outp(struct n struct nv50_head_atom *armh = nv50_head_atom(old_crtc_state); struct nv50_head_atom *asyh = nv50_head_atom(new_crtc_state); struct nv50_outp_atom *outp_atom; - struct nouveau_encoder *outp = - nv50_real_outp(nv50_head_atom_get_encoder(armh)); - struct drm_encoder *encoder = &outp->base.base; + struct nouveau_encoder *outp; + struct drm_encoder *encoder, *enc; + + enc = nv50_head_atom_get_encoder(armh); + if (!enc) + continue; + + outp = nv50_real_outp(enc); + if (!outp) + continue; + + encoder = &outp->base.base;
if (!asyh->clr.crc) continue; @@ -443,8 +452,16 @@ void nv50_crc_atomic_set(struct nv50_hea struct drm_device *dev = crtc->dev; struct nv50_crc *crc = &head->crc; const struct nv50_crc_func *func = nv50_disp(dev)->core->func->crc; - struct nouveau_encoder *outp = - nv50_real_outp(nv50_head_atom_get_encoder(asyh)); + struct nouveau_encoder *outp; + struct drm_encoder *encoder; + + encoder = nv50_head_atom_get_encoder(asyh); + if (!encoder) + return; + + outp = nv50_real_outp(encoder); + if (!outp) + return;
func->set_src(head, outp->or, nv50_crc_source_type(outp, asyh->crc.src), &crc->ctx[crc->ctx_idx]);