linux-kernel - [PATCH v2] media: platform: mtk-mdp3: Add missing check and free for ida

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Message-Id: <20230209090922.8829-1-jiasheng@iscas.ac.cn>
Date:   Thu,  9 Feb 2023 17:09:22 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     mchehab@...nel.org, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com, moudy.ho@...iatek.com,
        daoyuan.huang@...iatek.com, hverkuil-cisco@...all.nl
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] media: platform: mtk-mdp3: Add missing check and free for ida_alloc

Add the check for the return value of the ida_alloc in order to avoid
NULL pointer dereference.
Moreover, free allocated "ctx->id" if mdp_m2m_open fails later in order
to avoid memory leak.

Fixes: 61890ccaefaf ("media: platform: mtk-mdp3: add MediaTek MDP3 driver")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog:

v1 -> v2:

1. Fix the check for the ida_alloc.
---
 drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c
index 5f74ea3b7a52..4785c897ee1d 100644
--- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c
+++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-m2m.c
@@ -567,6 +567,11 @@ static int mdp_m2m_open(struct file *file)
 	}
 
 	ctx->id = ida_alloc(&mdp->mdp_ida, GFP_KERNEL);
+	if (ctx->id < 0) {
+		ret = ctx->id;
+		goto err_unlock_mutex;
+	}
+
 	ctx->mdp_dev = mdp;
 
 	v4l2_fh_init(&ctx->fh, vdev);
@@ -617,6 +622,8 @@ static int mdp_m2m_open(struct file *file)
 	v4l2_fh_del(&ctx->fh);
 err_exit_fh:
 	v4l2_fh_exit(&ctx->fh);
+	ida_free(&mdp->mdp_ida, ctx->id);
+err_unlock_mutext:
 	mutex_unlock(&mdp->m2m_lock);
 err_free_ctx:
 	kfree(ctx);
-- 
2.25.1