Re: [PATCH] of: unittest: Remove refcount underflow tests

[Rob Herring]

On Sun, Nov 01, 2026 at 01:19:29PM +0100, Danilo Krummrich wrote:
> With CONFIG_OF_UNITTEST=y and CONFIG_BUG_ON_DATA_CORRUPTION=y, the
> machine no longer boots after commit 5b5224220747 ("refcount: Use
> CONFIG_BUG_ON_DATA_CORRUPTION for UAF-related errors").
> 
> of_unittest_lifecycle() deliberately calls of_node_put() after the
> node's reference count has reached zero. The test expects a warning and
> continues to check that a subsequent put does not produce another
> warning. With BUG_ON_DATA_CORRUPTION enabled, refcount underflow now
> triggers BUG() instead. This panics the kernel during boot:
> 
> 	kernel BUG at lib/refcount.c:37!
> 	Oops: invalid opcode: 0000 [#1] SMP NOPTI
> 	CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Tainted: G                 N  7.3.0+ #14 PREEMPT(full)
> 	RIP: 0010:refcount_warn_saturate+0x89/0x90
> 	Call Trace:
> 	 of_unittest_lifecycle+0x158/0x310
> 	 of_unittest+0x105/0x130
> 	 do_one_initcall+0x127/0x350
> 	 do_initcall_level+0x7c/0xe0
> 	 do_initcalls+0x59/0xa0
> 	 kernel_init_freeable+0x118/0x1a0
> 	 kernel_init+0x1f/0x140
> 	Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> 
> Remove the refcount underflow tests, which exercise the refcount
> implementation rather than OF-specific behavior.
> 
> Fixes: 5b5224220747 ("refcount: Use CONFIG_BUG_ON_DATA_CORRUPTION for UAF-related errors")
> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
> ---
>  drivers/of/unittest.c | 43 -------------------------------------------
>  1 file changed, 43 deletions(-)

Applied, thanks.

Rob