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    Subject[PATCH 5.15 573/779] rpmsg: char: Add mutex protection for rpmsg_eptdev_open()
    Date
    From: Shengjiu Wang <shengjiu.wang@nxp.com>

    [ Upstream commit abe13e9a561d6b3e82b21362c0d6dd3ecd8a5b13 ]

    There is no mutex protection for rpmsg_eptdev_open(),
    especially for eptdev->ept read and write operation.
    It may cause issues when multiple instances call
    rpmsg_eptdev_open() in parallel,the return state
    may be success or EBUSY.

    Fixes: 964e8bedd5a1 ("rpmsg: char: Return an error if device already open")
    Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
    Link: https://lore.kernel.org/r/1653104105-16779-1-git-send-email-shengjiu.wang@nxp.com
    Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/rpmsg/rpmsg_char.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
    index 49dd5a200998..88c985f9e73a 100644
    --- a/drivers/rpmsg/rpmsg_char.c
    +++ b/drivers/rpmsg/rpmsg_char.c
    @@ -127,8 +127,11 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
    struct rpmsg_device *rpdev = eptdev->rpdev;
    struct device *dev = &eptdev->dev;

    - if (eptdev->ept)
    + mutex_lock(&eptdev->ept_lock);
    + if (eptdev->ept) {
    + mutex_unlock(&eptdev->ept_lock);
    return -EBUSY;
    + }

    get_device(dev);

    @@ -136,11 +139,13 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
    if (!ept) {
    dev_err(dev, "failed to open %s\n", eptdev->chinfo.name);
    put_device(dev);
    + mutex_unlock(&eptdev->ept_lock);
    return -EINVAL;
    }

    eptdev->ept = ept;
    filp->private_data = eptdev;
    + mutex_unlock(&eptdev->ept_lock);

    return 0;
    }
    --
    2.35.1


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