[PATCH v2] arm64: io: Reject non-user protection in ioremap_prot()

[Will Deacon]

On Fri, 11 Sep 2026 09:58:59 +0800, Zeng Heng wrote:
> Mapping a stack-top page via /dev/mem with PROT_NONE and then
> reading that process's /proc/<pid>/cmdline triggers a spurious WARN
> in ioremap_prot() through generic_access_phys():
> 
>   WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys
>   Call trace:
>     generic_access_phys+0x1c8/0x228 (P)
>     __access_remote_vm+0x2b4/0x398
>     access_remote_vm+0x14/0x30
>     get_mm_cmdline+0xf8/0x2a0
>     proc_pid_cmdline_read+0x68/0x120
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64: io: Reject non-user protection in ioremap_prot()
      https://git.kernel.org/arm64/c/bb756b11ad63

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
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