CVE-2026-53158misc: fastrpc: Fix NULL pointer dereference in rpmsg callback

Official description

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: Fix NULL pointer dereference in rpmsg callback A NULL pointer dereference was observed on Hawi at boot when the DSP sends a glink message before fastrpc_rpmsg_probe() has completed initialization: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000178 pc : _raw_spin_lock_irqsave+0x34/0x8c lr : fastrpc_rpmsg_callback+0x3c/0xcc [fastrpc] ... Call trace: _raw_spin_lock_irqsave+0x34/0x8c (P) fastrpc_rpmsg_callback+0x3c/0xcc [fastrpc] qcom_glink_native_rx+0x538/0x6a4 qcom_glink_smem_intr+0x14/0x24 [qcom_glink_smem] The faulting address 0x178 corresponds to the lock variable inside struct fastrpc_channel_ctx, confirming that cctx is NULL when fastrpc_rpmsg_callback() attempts to take the spinlock. There are two issues here. First, dev_set_drvdata() is called before spin_lock_init() and idr_init(), leaving a window where the callback can retrieve a valid cctx pointer but operate on an uninitialized spinlock. Second, the rpmsg channel becomes live as soon as the driver is bound, so fastrpc_rpmsg_callback() can fire before dev_set_drvdata() is called at all, resulting in dev_get_drvdata() returning NULL. Fix both issues by moving all cctx initialization ahead of dev_set_drvdata() so the structure is fully initialized before it becomes visible to the callback, and add a NULL check in fastrpc_rpmsg_callback() as a guard against any remaining window.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a3d91218ccca1e990bfb737b5a6da23f0afba22b
• https://git.kernel.org/stable/c/0d8c64511fd45690c5326f013710efcb4f73a97e
• https://git.kernel.org/stable/c/150bf6f1193c69252580c19d3b3cd631ddce61d7
• https://git.kernel.org/stable/c/8fb4a23df5b7c02929b62e5dbc270ec7c42b8134
• https://git.kernel.org/stable/c/4bfdf0a9855df55e9e031ca6a25b855820590c70
• https://git.kernel.org/stable/c/d5de9cb5355db36438edc621dde3673e3f235767
• https://git.kernel.org/stable/c/d77583ca33299fede0c194744ef2284e7ba5b763
• https://git.kernel.org/stable/c/5401fb4fe10fac6134c308495df18ed74aebb9c4