Re: [PATCH v2 0/3] drm/display: bridge_connector: get/put the stored bridges: fix NULL pointer regression

Re: [PATCH v2 0/3] drm/display: bridge_connector: get/put the stored bridges: fix NULL pointer regression

[Geert Uytterhoeven]

Hi Luca,

On Fri, 17 Oct 2025 at 18:58, Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
> A patch of mine recently merged in drm-misc-next [1] has a NULL pointer
> deref regression (reported here [2] and here [3]). Being in lack of a quick
> fix, I sent a revert proposal [4].
>
> The revert proposal has no answers currenty, and in the meanwhile I have a
> patch that implements the original idea but without the same bug. So here's
> a v2 series with:
>
>  - the same revert patch
>  - the original patch but rewritten without the same bug (and even simpler)
>
> Also the re-written patch is now split in two for clarity because it was
> doing two somewhat different things.
>
> [1] https://lore.kernel.org/all/20250926-drm-bridge-alloc-getput-bridge-connector-v2-1-138b4bb70576@bootlin.com/
> [2] https://lore.kernel.org/lkml/336fbfdd-c424-490e-b5d1-8ee84043dc80@samsung.com/
> [3] https://lore.kernel.org/lkml/CA+G9fYuKHp3QgPKjgFY3TfkDdh5Vf=Ae5pCW+eU41Bu=D7th2g@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/20251016-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v1-1-81d6984c5361@bootlin.com/
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> ---
> Changes in v2:
> - No changes to the revert patch
> - Added the (corrected) patch introducing the same feature as the original
>   buggy patch, and also split it in two fir clarity
> - Link to v1: https://lore.kernel.org/r/20251016-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v1-1-81d6984c5361@bootlin.com

Thanks, this fixes the crash I experienced on Koelsch (R-Car M2-W)
(https://lore.kernel.org/CAMuHMdW=zEi4XjG2Qrvj=jCa9LPBRU7HBTwEQVbe0zoz5mV_XA@mail.gmail.com)

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds