When a connector is connected but inactive (e.g., disabled by desktop environments), pipe_ctx->stream_res.tg will be destroyed. Then, reading odm_combine_segments causes kernel NULL pointer dereference.

BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 16 UID: 0 PID: 26474 Comm: cat Not tainted 6.17.0+ #2 PREEMPT(lazy) e6a17af9ee6db7c63e9d90dbe5b28ccab67520c6 Hardware name: LENOVO 21Q4/LNVNB161216, BIOS PXCN25WW 03/27/2025 RIP: 0010:odm_combine_segments_show+0x93/0xf0 [amdgpu] Code: 41 83 b8 b0 00 00 00 01 75 6e 48 98 ba a1 ff ff ff 48 c1 e0 0c 48 8d 8c 07 d8 02 00 00 48 85 c9 74 2d 48 8b bc 07 f0 08 00 00 <48> 8b 07 48 8b 80 08 02 00> RSP: 0018:ffffd1bf4b953c58 EFLAGS: 00010286 RAX: 0000000000005000 RBX: ffff8e35976b02d0 RCX: ffff8e3aeed052d8 RDX: 00000000ffffffa1 RSI: ffff8e35a3120800 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff8e3580eb0000 R09: ffff8e35976b02d0 R10: ffffd1bf4b953c78 R11: 0000000000000000 R12: ffffd1bf4b953d08 R13: 0000000000040000 R14: 0000000000000001 R15: 0000000000000001 FS: 00007f44d3f9f740(0000) GS:ffff8e3caa47f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000006485c2000 CR4: 0000000000f50ef0 PKRU: 55555554 Call Trace: <TASK> seq_read_iter+0x125/0x490 ? __alloc_frozen_pages_noprof+0x18f/0x350 seq_read+0x12c/0x170 full_proxy_read+0x51/0x80 vfs_read+0xbc/0x390 ? __handle_mm_fault+0xa46/0xef0 ? do_syscall_64+0x71/0x900 ksys_read+0x73/0xf0 do_syscall_64+0x71/0x900 ? count_memcg_events+0xc2/0x190 ? handle_mm_fault+0x1d7/0x2d0 ? do_user_addr_fault+0x21a/0x690 ? exc_page_fault+0x7e/0x1a0 entry_SYSCALL_64_after_hwframe+0x6c/0x74 RIP: 0033:0x7f44d4031687 Code: 48 89 fa 4c 89 df e8 58 b3 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00> RSP: 002b:00007ffdb4b5f0b0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f44d3f9f740 RCX: 00007f44d4031687 RDX: 0000000000040000 RSI: 00007f44d3f5e000 RDI: 0000000000000003 RBP: 0000000000040000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007f44d3f5e000 R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000040000 </TASK> Modules linked in: tls tcp_diag inet_diag xt_mark ccm snd_hrtimer snd_seq_dummy snd_seq_midi snd_seq_oss snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device x> snd_hda_codec_atihdmi snd_hda_codec_realtek_lib lenovo_wmi_helpers think_lmi snd_hda_codec_generic snd_hda_codec_hdmi snd_soc_core kvm snd_compress uvcvideo sn> platform_profile joydev amd_pmc mousedev mac_hid sch_fq_codel uinput i2c_dev parport_pc ppdev lp parport nvme_fabrics loop nfnetlink ip_tables x_tables dm_cryp> CR2: 0000000000000000 ---[ end trace 0000000000000000 ]--- RIP: 0010:odm_combine_segments_show+0x93/0xf0 [amdgpu] Code: 41 83 b8 b0 00 00 00 01 75 6e 48 98 ba a1 ff ff ff 48 c1 e0 0c 48 8d 8c 07 d8 02 00 00 48 85 c9 74 2d 48 8b bc 07 f0 08 00 00 <48> 8b 07 48 8b 80 08 02 00> RSP: 0018:ffffd1bf4b953c58 EFLAGS: 00010286 RAX: 0000000000005000 RBX: ffff8e35976b02d0 RCX: ffff8e3aeed052d8 RDX: 00000000ffffffa1 RSI: ffff8e35a3120800 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff8e3580eb0000 R09: ffff8e35976b02d0 R10: ffffd1bf4b953c78 R11: 0000000000000000 R12: ffffd1bf4b953d08 R13: 0000000000040000 R14: 0000000000000001 R15: 0000000000000001 FS: 00007f44d3f9f740(0000) GS:ffff8e3caa47f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000006485c2000 CR4: 0000000000f50ef0 PKRU: 55555554

Fix this by checking pipe_ctx->stream_res.tg before dereferencing.

Fixes: 07926ba8a44f ("drm/amd/display: Add debugfs interface for ODM combine info") Cc: stable@vger.kernel.org Signed-off-by: Rong Zhang i@rong.moe --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c index f263e1a4537e1..00dac862b665a 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c @@ -1302,7 +1302,8 @@ static int odm_combine_segments_show(struct seq_file *m, void *unused) if (connector->status != connector_status_connected) return -ENODEV;

- if (pipe_ctx != NULL && pipe_ctx->stream_res.tg->funcs->get_odm_combine_segments) + if (pipe_ctx && pipe_ctx->stream_res.tg && + pipe_ctx->stream_res.tg->funcs->get_odm_combine_segments) pipe_ctx->stream_res.tg->funcs->get_odm_combine_segments(pipe_ctx->stream_res.tg, &segments);

seq_printf(m, "%d\n", segments);

base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787