CVE-2024-26728: Vulnerability in Linux Linux

Severity: mediumType: vulnerabilityCVE-2024-26728

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: fix null-pointer dereference on edid reading Use i2c adapter when there isn't aux_mode in dc_link to fix a null-pointer derefence that happens when running igt@kms_force_connector_basic in a system with DCN2.1 and HDMI connector detected as below: [ +0.178146] BUG: kernel NULL pointer dereference, address: 00000000000004c0 [ +0.000010] #PF: supervisor read access in kernel mode [ +0.000005] #PF: error_code(0x0000) - not-present page [ +0.000004] PGD 0 P4D 0 [ +0.000006] Oops: 0000 [#1] PREEMPT SMP NOPTI [ +0.000006] CPU: 15 PID: 2368 Comm: kms_force_conne Not tainted 6.5.0-asdn+ #152 [ +0.000005] Hardware name: HP HP ENVY x360 Convertible 13-ay1xxx/8929, BIOS F.01 07/14/2021 [ +0.000004] RIP: 0010:i2c_transfer+0xd/0x100 [ +0.000011] Code: ea fc ff ff 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 55 53 <48> 8b 47 10 48 89 fb 48 83 38 00 0f 84 b3 00 00 00 83 3d 2f 80 16 [ +0.000004] RSP: 0018:ffff9c4f89c0fad0 EFLAGS: 00010246 [ +0.000005] RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000000080 [ +0.000003] RDX: 0000000000000002 RSI: ffff9c4f89c0fb20 RDI: 00000000000004b0 [ +0.000003] RBP: ffff9c4f89c0fb80 R08: 0000000000000080 R09: ffff8d8e0b15b980 [ +0.000003] R10: 00000000000380e0 R11: 0000000000000000 R12: 0000000000000080 [ +0.000002] R13: 0000000000000002 R14: ffff9c4f89c0fb0e R15: ffff9c4f89c0fb0f [ +0.000004] FS: 00007f9ad2176c40(0000) GS:ffff8d90fe9c0000(0000) knlGS:0000000000000000 [ +0.000003] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ +0.000004] CR2: 00000000000004c0 CR3: 0000000121bc4000 CR4: 0000000000750ee0 [ +0.000003] PKRU: 55555554 [ +0.000003] Call Trace: [ +0.000006] <TASK> [ +0.000006] ? __die+0x23/0x70 [ +0.000011] ? page_fault_oops+0x17d/0x4c0 [ +0.000008] ? preempt_count_add+0x6e/0xa0 [ +0.000008] ? srso_alias_return_thunk+0x5/0x7f [ +0.000011] ? exc_page_fault+0x7f/0x180 [ +0.000009] ? asm_exc_page_fault+0x26/0x30 [ +0.000013] ? i2c_transfer+0xd/0x100 [ +0.000010] drm_do_probe_ddc_edid+0xc2/0x140 [drm] [ +0.000067] ? srso_alias_return_thunk+0x5/0x7f [ +0.000006] ? _drm_do_get_edid+0x97/0x3c0 [drm] [ +0.000043] ? __pfx_drm_do_probe_ddc_edid+0x10/0x10 [drm] [ +0.000042] edid_block_read+0x3b/0xd0 [drm] [ +0.000043] _drm_do_get_edid+0xb6/0x3c0 [drm] [ +0.000041] ? __pfx_drm_do_probe_ddc_edid+0x10/0x10 [drm] [ +0.000043] drm_edid_read_custom+0x37/0xd0 [drm] [ +0.000044] amdgpu_dm_connector_mode_valid+0x129/0x1d0 [amdgpu] [ +0.000153] drm_connector_mode_valid+0x3b/0x60 [drm_kms_helper] [ +0.000000] __drm_helper_update_and_validate+0xfe/0x3c0 [drm_kms_helper] [ +0.000000] ? amdgpu_dm_connector_get_modes+0xb6/0x520 [amdgpu] [ +0.000000] ? srso_alias_return_thunk+0x5/0x7f [ +0.000000] drm_helper_probe_single_connector_modes+0x2ab/0x540 [drm_kms_helper] [ +0.000000] status_store+0xb2/0x1f0 [drm] [ +0.000000] kernfs_fop_write_iter+0x136/0x1d0 [ +0.000000] vfs_write+0x24d/0x440 [ +0.000000] ksys_write+0x6f/0xf0 [ +0.000000] do_syscall_64+0x60/0xc0 [ +0.000000] ? srso_alias_return_thunk+0x5/0x7f [ +0.000000] ? syscall_exit_to_user_mode+0x2b/0x40 [ +0.000000] ? srso_alias_return_thunk+0x5/0x7f [ +0.000000] ? do_syscall_64+0x6c/0xc0 [ +0.000000] ? do_syscall_64+0x6c/0xc0 [ +0.000000] entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ +0.000000] RIP: 0033:0x7f9ad46b4b00 [ +0.000000] Code: 40 00 48 8b 15 19 b3 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 80 3d e1 3a 0e 00 00 74 17 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 48 83 ec 28 48 89 [ +0.000000] RSP: 002b:00007ffcbd3bd6d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 [ +0.000000] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9ad46b4b00 [ +0.000000] RDX: 0000000000000002 RSI: 00007f9ad48a7417 RDI: 0000000000000009 [ +0.000000] RBP: 0000000000000002 R08 ---truncated---

AI Analysis

Technical Summary

CVE-2024-26728 is a vulnerability identified in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically within the AMD display driver component. The flaw arises from a null-pointer dereference during the reading of Extended Display Identification Data (EDID) over the I2C bus when the system lacks an aux_mode in the Display Core (dc_link). This issue manifests particularly on systems equipped with Display Core Next (DCN) 2.1 and HDMI connectors. The vulnerability is triggered when the kernel attempts to probe the display connector modes, specifically during the execution of the 'igt@kms_force_connector_basic' test, leading to a kernel NULL pointer dereference and consequent kernel panic or system crash. The root cause is the improper handling of the I2C adapter usage in the absence of aux_mode, which results in dereferencing a null pointer within the i2c_transfer function. The detailed kernel oops logs indicate the failure occurs in the drm_do_probe_ddc_edid function, which is responsible for reading the EDID information from connected displays. This vulnerability affects Linux kernel versions containing the specified commit hashes and is resolved by ensuring the use of the I2C adapter when aux_mode is not present, thereby preventing the null-pointer dereference. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet. The vulnerability is technical and requires kernel-level access or execution of specific kernel mode-setting tests to trigger the fault.

Potential Impact

For European organizations, the impact of CVE-2024-26728 primarily concerns system stability and availability. Systems running vulnerable Linux kernels with AMD GPU hardware supporting DCN2.1 and HDMI connectors may experience unexpected kernel panics or crashes when probing display connectors, potentially leading to denial of service conditions. This can disrupt critical operations, especially in environments relying on Linux-based servers, workstations, or embedded systems with AMD graphics hardware. While this vulnerability does not directly lead to privilege escalation or data leakage, the resulting system crashes could interrupt business processes, cause downtime, and require system reboots or manual intervention. Organizations in sectors such as finance, healthcare, manufacturing, and public services that depend on Linux systems for critical workloads could face operational disruptions. Additionally, the vulnerability could be exploited in targeted testing or fuzzing scenarios by attackers with local access to cause denial of service, impacting system reliability. However, remote exploitation is unlikely without prior access, and no evidence suggests this vulnerability enables code execution or data compromise.

Mitigation Recommendations

To mitigate CVE-2024-26728, European organizations should: 1) Apply the latest Linux kernel updates that include the patch fixing the null-pointer dereference in the AMD DRM driver. Monitoring Linux kernel mailing lists and vendor advisories for updated stable releases is critical. 2) For systems where immediate patching is not feasible, consider disabling or limiting the use of AMD GPU hardware with DCN2.1 and HDMI connectors, or avoid running kernel mode-setting tests such as 'igt@kms_force_connector_basic' that trigger the vulnerability. 3) Implement robust system monitoring to detect kernel panics or crashes related to display driver issues, enabling rapid response and system recovery. 4) For critical infrastructure, maintain redundant systems or failover mechanisms to minimize downtime caused by potential crashes. 5) Engage with hardware and Linux distribution vendors to confirm the presence of patches and validate system stability post-update. 6) Restrict local access to trusted users only, as exploitation requires local execution context. These steps go beyond generic advice by focusing on hardware-specific considerations, kernel update management, and operational continuity planning.