From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6D0213E5A31 for ; Mon, 25 May 2026 09:52:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779702779; cv=none; b=oXCMQsUErxsVQQBalcVYlAk23LtU/QrYU+56yz61F5L8T6mrJftRVapigsYVyCldVLgqtADvHyRFzAElTQNe/A7tlzlueJETwIrQV8HghJmxAiz0oRHqKFfnl0ho7xep7J4RckqU5QsOzju97Zq7ZReTjYkCscor6DZiisaAohQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779702779; c=relaxed/simple; bh=YXwLVmvrPT3CxIUwe1z2kjZT4+cCRWaplcDqgHQKXS4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EDR8ZQ+LyBhRFzYsjidDQuc45O3XtW3cmNBuS2a4/L6AWSEHvarI1qTdskdX5qS0gm5IaazR5B1F3jK3trmAg2LbSVU5mL7WFIsckzeCkphrJHGvUSw5CQbz5nqAUqJQxnLEDLudy+Xqr9KWUCjcmZRLo5wfFobVU4XZnrlv33E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=CTD236eX; arc=none smtp.client-ip=209.85.214.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CTD236eX" Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-2ba6485d219so72093805ad.3 for ; Mon, 25 May 2026 02:52:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779702778; x=1780307578; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=v2KznrLCQ77VZ51Z4KvrxVufB2DqA7HTlU0nEjlF/zw=; b=CTD236eXwI4Dgzt3N534Wd/Pr09C2fNX4w8CgDnjYyvNwOUbyIk8mCi13rUVwz1Rr0 rxKXmosAkTxyjxA4ezwiAAEoAhUaXteqaAmzD1ferJ0iDZMJpCkYFQABO+Nx3PBElMLc CX8BEDb7+s9L/LEhHzQHGvYRzDBBQzlDxplR7UECqvRbRlntVChEogoqvdfRz7ulr7P8 IECb5UHV0HJjI9YVQ6Uujy5HGNtyOpZ/+fMOa7NCqPMh02htLyMKU6qw6wWonDrtav4K 6zpTBJYpup7AlGWgAM7qHh/D3/FedlnqgBxpsTr/nOPiXJ6Lw5EwnMK6a3INOMG6LNcA 0tIw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779702778; x=1780307578; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=v2KznrLCQ77VZ51Z4KvrxVufB2DqA7HTlU0nEjlF/zw=; b=L8o59LsVaD9DKYfh53p5IF+2g4zFulwW++G6ErLB2X1jTVs4pEjrXUAzPI/YGf/KYp +C8DPeSl31IHkJ6iZBlgkQXNID0M3pDN6ME8Hx5Sb1ka4OnyPKUxJawyfLffEt8NFB9i glJXreBaY6SCw0fsDc+JTBslNWhKTWjs+RuDn8OpxfS0l8rtRrMZVun7pfM4YtNy6UlG /zI5cU3GnQvWg3zPBAU8gLw2sbQZwz3u8xd8YIrQd8oxXiquQ+UvA0LgZxagSRJ6plOd C+u4E5XGgCril1H5tw7se7z+iHa3LmDUCEI8iiC38Rhqi2LwXcoLmO+0QDNuZwNsrsXG r75Q== X-Forwarded-Encrypted: i=1; AFNElJ8qi6nXeHjjKna60wP9Jvwu+SgJhOIABHZmL2aWHmKHy8pjP8HFh90ywNlQCFoi7crT4xjg+nQCRC62YTw=@vger.kernel.org X-Gm-Message-State: AOJu0YyWejHBCWIB7X+WOB1OazPYa6UoNejEeuLuMwfe+iAyS21noSgv vIlsrSXQ90LlNqVPV4tJQF4drw3Bj4c4RtbhfQFv1u0U1bf8kj3X2aes X-Gm-Gg: Acq92OHR08pyZm16uO3UEkz46mQNrmyO1bZ+/J1XmLMx4IYzR1f3oVuzC5aEdoIleg5 HXUPgcsJ1UlqUbXPbuCFT6vAag3lhm75Cv5xG0n+9LCLA5z8cPZWJ/FLX7Cq3tjciqMmW8qlvbK JPjkllGw+xhvKjK/voDscmwARaZr7woUf/b1sEcQ8yh8Pfi/EYrWYAIlbj+FA+fXRtTRNyNzKeY +AvSBc5+Eei9+lmJEJdImRHvwPxOacsny6n70jinSBNK/Dp5k42css3DkOisCO7qS8GLk1lsun4 loZZSyBtqjsltc6rc6TiBaUQifuzJSW23Igs57OCA/YUf44kXKgqqdfgWsSW40ZAM+6DQxfESkP uOum1DfH3vNoIijPxVJFlTJ6EqN/8IMdr/Z4G54jEAGAirXNiTckou4rvn/nR/+mgz63Xx5KMKB YADdst4B17fFIFkRD4+siU X-Received: by 2002:a17:903:1ae3:b0:2ba:bfc:76a8 with SMTP id d9443c01a7336-2beb057f8c9mr151250385ad.16.1779702777738; Mon, 25 May 2026 02:52:57 -0700 (PDT) Received: from rockpi-5b ([45.112.0.230]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2beb58b2cd6sm92533615ad.52.2026.05.25.02.52.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 02:52:56 -0700 (PDT) From: Anand Moon To: Neil Armstrong , Mauro Carvalho Chehab , Greg Kroah-Hartman , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Maxime Jourdan , Hans Verkuil , linux-media@vger.kernel.org (open list:MESON VIDEO DECODER DRIVER FOR AMLOGIC SOCS), linux-amlogic@lists.infradead.org (open list:MESON VIDEO DECODER DRIVER FOR AMLOGIC SOCS), linux-staging@lists.linux.dev (open list:STAGING SUBSYSTEM), linux-arm-kernel@lists.infradead.org (moderated list:ARM/Amlogic Meson SoC support), linux-kernel@vger.kernel.org (open list) Cc: Anand Moon , Nicolas Dufresne , Sashiko Subject: [PATCH v5 3/6] media: meson: vdec: Set cur_sess before hardware vdec_poweron() Date: Mon, 25 May 2026 15:21:51 +0530 Message-ID: <20260525095216.12078-4-linux.amoon@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260525095216.12078-1-linux.amoon@gmail.com> References: <20260525095216.12078-1-linux.amoon@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit vdec_poweron() initializes hardware and unmasks device interrupts. If an interrupt fires before core->cur_sess is set, vdec_isr() dereferences a NULL pointer when updating sess->last_irq_jiffies, leading to a kernel panic. Fix this by assigning core->cur_sess and updating sess->status under core->lock before calling vdec_poweron(). This ensures the interrupt handler always sees a valid session pointer. On the error path, clear core->cur_sess and reset sess->status to STATUS_STOPPED to avoid stale references. Following change also strengthens the hardware exclusivity check by holding core->lock during session assignment, preventing concurrent sessions from racing through cur_sess == NULL and corrupting hardware state. Cc: Nicolas Dufresne Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260521090944.F35401F00A3D@smtp.kernel.org/ Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver") Signed-off-by: Anand Moon --- v5: [Critical] Race condition between hardware power-on and `core->cur_sess` initialization leads to a NULL pointer dereference in the IRQ handler. --- drivers/staging/media/meson/vdec/vdec.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c index e72f54af026e..52ace4de967c 100644 --- a/drivers/staging/media/meson/vdec/vdec.c +++ b/drivers/staging/media/meson/vdec/vdec.c @@ -334,6 +334,11 @@ static int vdec_start_streaming(struct vb2_queue *q, unsigned int count) atomic_set(&sess->esparser_queued_bufs, 0); v4l2_ctrl_s_ctrl(sess->ctrl_min_buf_capture, 1); + mutex_lock(&core->lock); + core->cur_sess = sess; + sess->status = STATUS_INIT; + mutex_unlock(&core->lock); + ret = vdec_poweron(sess); if (ret) goto vififo_free; @@ -344,12 +349,14 @@ static int vdec_start_streaming(struct vb2_queue *q, unsigned int count) sess->recycle_thread = kthread_run(vdec_recycle_thread, sess, "vdec_recycle"); - sess->status = STATUS_INIT; - core->cur_sess = sess; schedule_work(&sess->esparser_queue_work); return 0; vififo_free: + mutex_lock(&core->lock); + core->cur_sess = NULL; + sess->status = STATUS_STOPPED; + mutex_unlock(&core->lock); dma_free_coherent(sess->core->dev, sess->vififo_size, sess->vififo_vaddr, sess->vififo_paddr); bufs_done: -- 2.50.1