[PATCH v3 2/2] ARM: mm: protect show_pte() in do_DataAbort() fallback path

[Russell King]

On Fri, Jun 26, 2026 at 03:30:48PM +0800, Qi Xi wrote:
> The do_DataAbort() fallback path handles FSR types not serviced by
> do_page_fault() (fsr_info entries with fn=do_bad). This path also
> calls show_pte() without holding mmap_read_lock, exposing it to
> the same use-after-free issue.
> 
> Since do_DataAbort() is an exception entry point that can be reached
> from contexts where sleeping is not allowed, use mmap_read_trylock().
> If the lock cannot be acquired, the page table dump is skipped.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Suggested-by: Yuanbin Xie <xieyuanbin1 at huawei.com>
> Signed-off-by: Qi Xi <xiqi2 at huawei.com>

Same reason as patch 1. We can't take locks.

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