CVE-2024-56608

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Fix out-of-bounds access in 'dcn21_link_encoder_create'

An issue was identified in the dcn21_link_encoder_create function where an out-of-bounds access could occur when the hpd_source index was used to reference the link_enc_hpd_regs array. This array has a fixed size and the index was not being checked against the array's bounds before accessing it.

This fix adds a conditional check to ensure that the hpd_source index is within the valid range of the link_enc_hpd_regs array. If the index is out of bounds, the function now returns NULL to prevent undefined behavior.

References:

[ 65.920507] ------------[ cut here ]------------ [ 65.920510] UBSAN: array-index-out-of-bounds in drivers/gpu/drm/amd/amdgpu/../display/dc/resource/dcn21/dcn21_resource.c:1312:29 [ 65.920519] index 7 is out of range for type 'dcn10_link_enc_hpd_registers [5]' [ 65.920523] CPU: 3 PID: 1178 Comm: modprobe Tainted: G OE 6.8.0-cleanershaderfeatureresetasdntipmi200nv2132 #13 [ 65.920525] Hardware name: AMD Majolica-RN/Majolica-RN, BIOS WMJ0429N_Weekly_20_04_2 04/29/2020 [ 65.920527] Call Trace: [ 65.920529] <TASK> [ 65.920532] dump_stack_lvl+0x48/0x70 [ 65.920541] dump_stack+0x10/0x20 [ 65.920543] __ubsan_handle_out_of_bounds+0xa2/0xe0 [ 65.920549] dcn21_link_encoder_create+0xd9/0x140 [amdgpu] [ 65.921009] link_create+0x6d3/0xed0 [amdgpu] [ 65.921355] create_links+0x18a/0x4e0 [amdgpu] [ 65.921679] dc_create+0x360/0x720 [amdgpu] [ 65.921999] ? dmi_matches+0xa0/0x220 [ 65.922004] amdgpu_dm_init+0x2b6/0x2c90 [amdgpu] [ 65.922342] ? console_unlock+0x77/0x120 [ 65.922348] ? dev_printk_emit+0x86/0xb0 [ 65.922354] dm_hw_init+0x15/0x40 [amdgpu] [ 65.922686] amdgpu_device_init+0x26a8/0x33a0 [amdgpu] [ 65.922921] amdgpu_driver_load_kms+0x1b/0xa0 [amdgpu] [ 65.923087] amdgpu_pci_probe+0x1b7/0x630 [amdgpu] [ 65.923087] local_pci_probe+0x4b/0xb0 [ 65.923087] pci_device_probe+0xc8/0x280 [ 65.923087] really_probe+0x187/0x300 [ 65.923087] __driver_probe_device+0x85/0x130 [ 65.923087] driver_probe_device+0x24/0x110 [ 65.923087] __driver_attach+0xac/0x1d0 [ 65.923087] ? __pfx___driver_attach+0x10/0x10 [ 65.923087] bus_for_each_dev+0x7d/0xd0 [ 65.923087] driver_attach+0x1e/0x30 [ 65.923087] bus_add_driver+0xf2/0x200 [ 65.923087] driver_register+0x64/0x130 [ 65.923087] ? __pfx_amdgpu_init+0x10/0x10 [amdgpu] [ 65.923087] __pci_register_driver+0x61/0x70 [ 65.923087] amdgpu_init+0x7d/0xff0 [amdgpu] [ 65.923087] do_one_initcall+0x49/0x310 [ 65.923087] ? kmalloc_trace+0x136/0x360 [ 65.923087] do_init_module+0x6a/0x270 [ 65.923087] load_module+0x1fce/0x23a0 [ 65.923087] init_module_from_file+0x9c/0xe0 [ 65.923087] ? init_module_from_file+0x9c/0xe0 [ 65.923087] idempotent_init_module+0x179/0x230 [ 65.923087] __x64_sys_finit_module+0x5d/0xa0 [ 65.923087] do_syscall_64+0x76/0x120 [ 65.923087] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 65.923087] RIP: 0033:0x7f2d80f1e88d [ 65.923087] Code: 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 73 b5 0f 00 f7 d8 64 89 01 48 [ 65.923087] RSP: 002b:00007ffc7bc1aa78 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 [ 65.923087] RAX: ffffffffffffffda RBX: 0000564c9c1db130 RCX: 00007f2d80f1e88d [ 65.923087] RDX: 0000000000000000 RSI: 0000564c9c1e5480 RDI: 000000000000000f [ 65.923087] RBP: 0000000000040000 R08: 0000000000000000 R09: 0000000000000002 [ 65.923087] R10: 000000000000000f R11: 0000000000000246 R12: 0000564c9c1e5480 [ 65.923087] R13: 0000564c9c1db260 R14: 0000000000000000 R15: 0000564c9c1e54b0 [ 65.923087] </TASK> [ 65.923927] ---[ end trace ]---

A low impact out-of-bounds access flaw was found in the AMD display (amdgpu) driver in the Linux kernel. In the dcn21_link_encoder_create function, the hpd_source index was used to reference the fixed-size link_enc_hpd_regs array without first validating that the index was within the array bounds, which could result in an out-of-bounds read and undefined behavior during GPU/display driver initialization on affected AMD hardware. Because the issue is reachable only locally during driver initialization on affected hardware, Red Hat Product Security has rated this flaw Low impact, which differs from the Important (CVSS 7.8) severity published in the upstream CVE record. All Red Hat products currently tracked for this flaw, including the Red Hat Enterprise Linux kernel and kernel-rt streams and the Hosted OpenShift offerings, have been assessed as not affected by this issue.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.