drm/exynos: vidi: use ctx->lock to protect struct vidi_context member variables related to memory alloc/free

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commit 52b330799e upstream.

Exynos Virtual Display driver performs memory alloc/free operations
without lock protection, which easily causes concurrency problem.

For example, use-after-free can occur in race scenario like this:
```
	CPU0				CPU1				CPU2
	----				----				----
  vidi_connection_ioctl()
    if (vidi->connection) // true
      drm_edid = drm_edid_alloc(); // alloc drm_edid
      ...
      ctx->raw_edid = drm_edid;
      ...
								drm_mode_getconnector()
								  drm_helper_probe_single_connector_modes()
								    vidi_get_modes()
								      if (ctx->raw_edid) // true
								        drm_edid_dup(ctx->raw_edid);
								          if (!drm_edid) // false
								          ...
				vidi_connection_ioctl()
				  if (vidi->connection) // false
				    drm_edid_free(ctx->raw_edid); // free drm_edid
				    ...
								          drm_edid_alloc(drm_edid->edid)
								            kmemdup(edid); // UAF!!
								            ...
```

To prevent these vulns, at least in vidi_context, member variables related
to memory alloc/free should be protected with ctx->lock.

Cc: <stable@vger.kernel.org>
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Jeongjun Park 2026-01-19 17:25:53 +09:00 • committed by Greg Kroah-Hartman

parent ba52646104

commit 0cd2c15574

1 changed files with 32 additions and 6 deletions

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38

drivers/gpu/drm/exynos/exynos_drm_vidi.c

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