Hi Laurent,
Thanks for the feedback.
-----Original Message----- From: Laurent Pinchart laurent.pinchart@ideasonboard.com Sent: 05 November 2024 16:02 Subject: Re: [PATCH v2 1/2] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()
Hi Biju,
Thank you for the patch.
On Tue, Nov 05, 2024 at 11:12:18AM +0000, Biju Das wrote:
The host_node pointer assigned and freed in adv7533_parse_dt() and later adv7533_attach_dsi() uses the same. Fix this issue by freeing the host_node in adv7533_attach_dsi() instead of adv7533_parse_dt().
Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device") Cc: stable@vger.kernel.org Signed-off-by: Biju Das biju.das.jz@bp.renesas.com
Changes in v2:
- Added the tag "Cc: stable@vger.kernel.org" in the sign-off area.
- Dropped Archit Taneja invalid Mail address
drivers/gpu/drm/bridge/adv7511/adv7533.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c index 4481489aaf5e..3e57ba838e5e 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c @@ -133,6 +133,7 @@ int adv7533_patch_cec_registers(struct adv7511 *adv)
int adv7533_attach_dsi(struct adv7511 *adv) {
- struct device_node *np __free(device_node) = adv->host_node;
This raises so many red flags. The function will free the node while the adv->host_node variable still points to it, opening the door to
I agree, adv->host_node still points to it and open again the door to use-after-free.
use-after-free. Furthermore, there's nothing in the function name that hints it will do this, callers can get surprised by this behaviour.
By looking at [1], it can free the node pointer when it returns from the function. As you said there is no hints from function name. __free(device_node) just tells to free the random device node assigned to the local variable.
[1] https://elixir.bootlin.com/linux/v6.12-rc5/source/include/linux/of.h#L138
I'm sure you can do better than this and fix the problem with readable code, not cryptic and error- prone constructs :-)
Agreed. Will fix the problem with readable code.
Cheers, Biju
struct device *dev = &adv->i2c_main->dev; struct mipi_dsi_host *host; struct mipi_dsi_device *dsi; @@ -181,8 +182,6 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv) if (!adv->host_node) return -ENODEV;
- of_node_put(adv->host_node);
- adv->use_timing_gen = !of_property_read_bool(np, "adi,disable-timing-generator");
-- Regards,
Laurent Pinchart