medium CVSS 5.5

CVE-2024-40916·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm/exynos: hdmi: report safe 640x480 mode as a fallback when no EDID found When reading EDID fails and driver reports no modes available, the DRM core adds an artificial 1024x786 mode to the connector. Unfortunately some variants of the Exynos HDMI (like the one in Exynos4 SoCs) are not able to drive such mode, so report a safe 640x480 mode instead of nothing in case of the EDID reading failure. This fixes the following issue observed on Trats2 board since commit 13d5b040363c ("drm/exynos: do not return negative values from .get_modes()"): [drm] Exynos DRM: using 11c00000.fimd device for DMA mapping operations exynos-drm exynos-drm: bound 11c00000.fimd (ops fimd_component_ops) exynos-drm exynos-drm: bound 12c10000.mixer (ops mixer_component_ops) exynos-dsi 11c80000.dsi: [drm:samsung_dsim_host_attach] Attached s6e8aa0 device (lanes:4 bpp:24 mode-flags:0x10b) exynos-drm exynos-drm: bound 11c80000.dsi (ops exynos_dsi_component_ops) exynos-drm exynos-drm: bound 12d00000.hdmi (ops hdmi_component_ops) [drm] Initialized exynos 1.1.0 20180330 for exynos-drm on minor 1 exynos-hdmi 12d00000.hdmi: [drm:hdmiphy_enable.part.0] *ERROR* PLL could not reach steady state panel-samsung-s6e8aa0 11c80000.dsi.0: ID: 0xa2, 0x20, 0x8c exynos-mixer 12c10000.mixer: timeout waiting for VSYNC ------------[ cut here ]------------ WARNING: CPU: 1 PID: 11 at drivers/gpu/drm/drm_atomic_helper.c:1682 drm_atomic_helper_wait_for_vblanks.part.0+0x2b0/0x2b8 [CRTC:70:crtc-1] vblank wait timed out Modules linked in: CPU: 1 PID: 11 Comm: kworker/u16:0 Not tainted 6.9.0-rc5-next-20240424 #14913 Hardware name: Samsung Exynos (Flattened Device Tree) Workqueue: events_unbound deferred_probe_work_func Call trace: unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x68/0x88 dump_stack_lvl from __warn+0x7c/0x1c4 __warn from warn_slowpath_fmt+0x11c/0x1a8 warn_slowpath_fmt from drm_atomic_helper_wait_for_vblanks.part.0+0x2b0/0x2b8 drm_atomic_helper_wait_for_vblanks.part.0 from drm_atomic_helper_commit_tail_rpm+0x7c/0x8c drm_atomic_helper_commit_tail_rpm from commit_tail+0x9c/0x184 commit_tail from drm_atomic_helper_commit+0x168/0x190 drm_atomic_helper_commit from drm_atomic_commit+0xb4/0xe0 drm_atomic_commit from drm_client_modeset_commit_atomic+0x23c/0x27c drm_client_modeset_commit_atomic from drm_client_modeset_commit_locked+0x60/0x1cc drm_client_modeset_commit_locked from drm_client_modeset_commit+0x24/0x40 drm_client_modeset_commit from __drm_fb_helper_restore_fbdev_mode_unlocked+0x9c/0xc4 __drm_fb_helper_restore_fbdev_mode_unlocked from drm_fb_helper_set_par+0x2c/0x3c drm_fb_helper_set_par from fbcon_init+0x3d8/0x550 fbcon_init from visual_init+0xc0/0x108 visual_init from do_bind_con_driver+0x1b8/0x3a4 do_bind_con_driver from do_take_over_console+0x140/0x1ec do_take_over_console from do_fbcon_takeover+0x70/0xd0 do_fbcon_takeover from fbcon_fb_registered+0x19c/0x1ac fbcon_fb_registered from register_framebuffer+0x190/0x21c register_framebuffer from __drm_fb_helper_initial_config_and_unlock+0x350/0x574 __drm_fb_helper_initial_config_and_unlock from exynos_drm_fbdev_client_hotplug+0x6c/0xb0 exynos_drm_fbdev_client_hotplug from drm_client_register+0x58/0x94 drm_client_register from exynos_drm_bind+0x160/0x190 exynos_drm_bind from try_to_bring_up_aggregate_device+0x200/0x2d8 try_to_bring_up_aggregate_device from __component_add+0xb0/0x170 __component_add from mixer_probe+0x74/0xcc mixer_probe from platform_probe+0x5c/0xb8 platform_probe from really_probe+0xe0/0x3d8 really_probe from __driver_probe_device+0x9c/0x1e4 __driver_probe_device from driver_probe_device+0x30/0xc0 driver_probe_device from __device_attach_driver+0xa8/0x120 __device_attach_driver from bus_for_each_drv+0x80/0xcc bus_for_each_drv from __device_attach+0xac/0x1fc __device_attach from bus_probe_device+0x8c/0x90 bus_probe_device from deferred_probe_work_func+0 ---truncated---

Severity
medium
Software
Kernel
Fixed in
6.9.6
Published
2024-07-12

Affected versions

From: 6.8.3

Until: 6.9.6

Fixed in: 6.9.6

How to fix this CVE

Update your Linux kernel to version 6.9.6 or later to resolve this display driver issue affecting Exynos HDMI hardware. This vulnerability impacts systems where EDID (Extended Display Identification Data) reading fails, causing the driver to attempt incompatible display modes that certain Exynos SoC variants cannot support, leading to kernel warnings and display initialization failures. Apply the kernel update through your distribution's package manager to restore proper HDMI fallback behavior.

sudo dnf update kernel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your installed kernel version with `uname -r` and compare against the fixed version 6.9.6 or later
  2. Step 2: Verify if your system uses Exynos HDMI hardware by checking `lspci | grep -i hdmi` or inspecting device tree bindings in `/proc/device-tree`
  3. Step 3: Search kernel logs for HDMI initialization errors with `sudo dmesg | grep -i hdmi` and look for 'PLL could not reach steady state' or 'timeout waiting for VSYNC' messages
  4. Step 4: Confirm the fix by upgrading to kernel 6.9.6+ and verifying no HDMI-related warnings appear in `sudo journalctl -xe | grep -i hdmi` after reboot

FAQ

What is CVE-2024-40916?

CVE-2024-40916 is a medium-severity Linux kernel vulnerability in the Exynos HDMI display driver where EDID reading failures cause the driver to attempt unsupported display resolutions (1024x768), triggering kernel warnings and display initialization timeouts on affected Exynos SoC variants like those in Samsung Exynos4-based devices.

Is CVE-2024-40916 being actively exploited?

No, CVE-2024-40916 is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and has no public exploit available. It is a reliability issue rather than a security exploit vector.

What versions of Kernel are affected by CVE-2024-40916?

Linux kernel versions 6.8.3 through 6.9.5 are affected. The vulnerability is fixed in kernel 6.9.6 and later stable releases.

How do I check if my server is vulnerable to CVE-2024-40916?

Run `uname -r` to check your kernel version; if it reports 6.8.3 through 6.9.5 and your system has Exynos HDMI hardware, you are vulnerable. Additionally, check `sudo dmesg | grep -E '(hdmiphy_enable|timeout waiting for VSYNC)' to see if the issue has manifested.

Does Defensia detect CVE-2024-40916?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-40916 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-64033CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/rtrs: Fix use-after-free in path file creation cleanup In the error path of rtrs_srv_create_path_files(), the sysfs root folders may already have been created and srv_path->kobj may already have been initialized. If a later step fails, the cleanup currently calls kobject_put(&srv_path->kobj) before rtrs_srv_destroy_once_sysfs_root_folders(srv_path). kobject_put() may drop the last reference to srv_path->kobj and invoke the release callback, rtrs_srv_release(), which frees srv_path. The following call to rtrs_srv_destroy_once_sysfs_root_folders(srv_path) then dereferences srv_path internally to access srv_path->srv, resulting in a use-after-free. This failure path is reached before rtrs_srv_create_path_files() returns success, so the successful-path lifetime handling is not involved. Fix this by destroying the sysfs root folders before calling kobject_put(&srv_path->kobj), so srv_path is still valid while the helper accesses it. This issue was found by a static analysis tool I am developing.
CVE-2026-64037CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled When the TLC notification disables AMSDU for a TID, the MLD driver sets max_tid_amsdu_len to the sentinel value 1. The TSO segmentation path in iwl_mld_tx_tso_segment() checks for zero but not for this sentinel, allowing it to reach the num_subframes calculation: num_subframes = (max_tid_amsdu_len + pad) / (subf_len + pad) = (1 + 2) / (1534 + 2) = 0 This zero propagates to iwl_tx_tso_segment() which sets: gso_size = num_subframes * mss = 0 Calling skb_gso_segment() with gso_size=0 creates over 32000 tiny segments from a single GSO skb. This floods the TX ring with ~1024 micro-frames (the rest are purged), creating a massive burst of TX completion events that can lead to memory corruption and a subsequent use-after-free in TCP's retransmit queue (refcount underflow in tcp_shifted_skb, NULL deref in tcp_rack_detect_loss). The MVM driver is immune because it checks mvmsta->amsdu_enabled before reaching the num_subframes calculation. The MLD driver has no equivalent bitmap check and relies solely on max_tid_amsdu_len, which does not catch the sentinel value. Fix this by detecting the sentinel value (max_tid_amsdu_len == 1) at the existing check and falling back to non-AMSDU TSO segmentation. Also add a WARN_ON_ONCE guard after the num_subframes division as defense-in-depth to catch any future code paths that produce zero through a different mechanism.
CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64035CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: igc: set tx buffer type for SMD frames Sashiko pointed out that igc_fpe_init_smd_frame() initializes igc_tx_buffer fields for an SMD skb, but does not set the buffer type: https://sashiko.dev/#/patchset/20260415025226.114115-1-kohei%40enjuk.jp Since igc_tx_buffer entries are reused, a stale XDP or XSK type can remain and make TX completion use the wrong cleanup path. Set the buffer type to IGC_TX_BUFFER_TYPE_SKB.
CVE-2026-64007CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: refresh tcphdr after skb_ensure_writable synproxy_tstamp_adjust() rewrites the TCP timestamp option in place and then patches the TCP checksum via inet_proto_csum_replace4() on the caller-supplied tcphdr pointer. Both ipv4_synproxy_hook() and ipv6_synproxy_hook() obtain that pointer with skb_header_pointer() before calling in, so it may either alias skb->head directly or point at the caller's on-stack _tcph buffer. Between obtaining the pointer and using it, the function calls skb_ensure_writable(skb, optend), which on a cloned or non-linear skb invokes pskb_expand_head() and frees the old skb->head. After that point the cached th is stale: caller (ipv[46]_synproxy_hook) th = skb_header_pointer(skb, ..., &_tcph) synproxy_tstamp_adjust(skb, protoff, th, ...) skb_ensure_writable(skb, optend) pskb_expand_head() /* kfree(old skb->head) */ ... inet_proto_csum_replace4(&th->check, ...) /* writes into freed head, or into the caller's stack copy leaving the on-wire checksum stale */ The option bytes are written through skb->data and are fine; only the checksum update goes through th and so lands in the wrong place. The result is either a write into freed slab memory or a packet leaving with a checksum that does not match its payload. Fix by re-deriving th from skb->data + protoff immediately after skb_ensure_writable() succeeds, so the subsequent checksum update targets the linear, writable header.

References

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