From: Łukasz Bartosik lb@semihalf.com
[ Upstream commit 458ec0c8f35963626ccd51c3d50b752de5f1b9d4 ]
Asus chromebook CX550 crashes during boot on v5.17-rc1 kernel. The root cause is null pointer defeference of bi_next in tgl_get_bw_info() in drivers/gpu/drm/i915/display/intel_bw.c.
BUG: kernel NULL pointer dereference, address: 000000000000002e PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 1 Comm: swapper/0 Tainted: G U 5.17.0-rc1 Hardware name: Google Delbin/Delbin, BIOS Google_Delbin.13672.156.3 05/14/2021 RIP: 0010:tgl_get_bw_info+0x2de/0x510 ... [ 2.554467] Call Trace: [ 2.554467] <TASK> [ 2.554467] intel_bw_init_hw+0x14a/0x434 [ 2.554467] ? _printk+0x59/0x73 [ 2.554467] ? _dev_err+0x77/0x91 [ 2.554467] i915_driver_hw_probe+0x329/0x33e [ 2.554467] i915_driver_probe+0x4c8/0x638 [ 2.554467] i915_pci_probe+0xf8/0x14e [ 2.554467] ? _raw_spin_unlock_irqrestore+0x12/0x2c [ 2.554467] pci_device_probe+0xaa/0x142 [ 2.554467] really_probe+0x13f/0x2f4 [ 2.554467] __driver_probe_device+0x9e/0xd3 [ 2.554467] driver_probe_device+0x24/0x7c [ 2.554467] __driver_attach+0xba/0xcf [ 2.554467] ? driver_attach+0x1f/0x1f [ 2.554467] bus_for_each_dev+0x8c/0xc0 [ 2.554467] bus_add_driver+0x11b/0x1f7 [ 2.554467] driver_register+0x60/0xea [ 2.554467] ? mipi_dsi_bus_init+0x16/0x16 [ 2.554467] i915_init+0x2c/0xb9 [ 2.554467] ? mipi_dsi_bus_init+0x16/0x16 [ 2.554467] do_one_initcall+0x12e/0x2b3 [ 2.554467] do_initcall_level+0xd6/0xf3 [ 2.554467] do_initcalls+0x4e/0x79 [ 2.554467] kernel_init_freeable+0xed/0x14d [ 2.554467] ? rest_init+0xc1/0xc1 [ 2.554467] kernel_init+0x1a/0x120 [ 2.554467] ret_from_fork+0x1f/0x30 [ 2.554467] </TASK> ... Kernel panic - not syncing: Fatal exception
Fixes: c64a9a7c05be ("drm/i915: Update memory bandwidth formulae") Signed-off-by: Łukasz Bartosik lb@semihalf.com Reviewed-by: Radhakrishna Sripada radhakrishna.sripada@intel.com Signed-off-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20220201153354.11971-1-lukasz.... (cherry picked from commit c247cd03898c4c43c3bce6d4014730403bc13032) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/display/intel_bw.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c index 37bd7b17f3d0b..f2fad199e2e0b 100644 --- a/drivers/gpu/drm/i915/display/intel_bw.c +++ b/drivers/gpu/drm/i915/display/intel_bw.c @@ -404,15 +404,17 @@ static int tgl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel int clpchgroup; int j;
- if (i < num_groups - 1) - bi_next = &dev_priv->max_bw[i + 1]; - clpchgroup = (sa->deburst * qi.deinterleave / num_channels) << i;
- if (i < num_groups - 1 && clpchgroup < clperchgroup) - bi_next->num_planes = (ipqdepth - clpchgroup) / clpchgroup + 1; - else - bi_next->num_planes = 0; + if (i < num_groups - 1) { + bi_next = &dev_priv->max_bw[i + 1]; + + if (clpchgroup < clperchgroup) + bi_next->num_planes = (ipqdepth - clpchgroup) / + clpchgroup + 1; + else + bi_next->num_planes = 0; + }
bi->num_qgv_points = qi.num_points; bi->num_psf_gv_points = qi.num_psf_points;