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    Subject[PATCH 5.8 276/633] nvmem: core: fix possibly memleak when use nvmem_cell_info_to_nvmem_cell()
    Date
    From: Vadym Kochan <vadym.kochan@plvision.eu>

    [ Upstream commit fc9eec4d643597cf4cb2fef17d48110e677610da ]

    Fix missing 'kfree_const(cell->name)' when call to
    nvmem_cell_info_to_nvmem_cell() in several places:

    * after nvmem_cell_info_to_nvmem_cell() failed during
    nvmem_add_cells()

    * during nvmem_device_cell_{read,write} when cell->name is
    kstrdup'ed() without calling kfree_const() at the end, but
    really there is no reason to do that 'dup, because the cell
    instance is allocated on the stack for some short period to be
    read/write without exposing it to the caller.

    So the new nvmem_cell_info_to_nvmem_cell_nodup() helper is introduced
    which is used to convert cell_info -> cell without name duplication as
    a lighweight version of nvmem_cell_info_to_nvmem_cell().

    Fixes: e2a5402ec7c6 ("nvmem: Add nvmem_device based consumer apis.")
    Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
    Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
    Signed-off-by: Vadym Kochan <vadym.kochan@plvision.eu>
    Link: https://lore.kernel.org/r/20200923204456.14032-1-vadym.kochan@plvision.eu
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/nvmem/core.c | 33 ++++++++++++++++++++++++---------
    1 file changed, 24 insertions(+), 9 deletions(-)

    diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
    index 394e75dede725..4aca5b4a87d75 100644
    --- a/drivers/nvmem/core.c
    +++ b/drivers/nvmem/core.c
    @@ -355,16 +355,14 @@ static void nvmem_cell_add(struct nvmem_cell *cell)
    blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
    }

    -static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
    - const struct nvmem_cell_info *info,
    - struct nvmem_cell *cell)
    +static int nvmem_cell_info_to_nvmem_cell_nodup(struct nvmem_device *nvmem,
    + const struct nvmem_cell_info *info,
    + struct nvmem_cell *cell)
    {
    cell->nvmem = nvmem;
    cell->offset = info->offset;
    cell->bytes = info->bytes;
    - cell->name = kstrdup_const(info->name, GFP_KERNEL);
    - if (!cell->name)
    - return -ENOMEM;
    + cell->name = info->name;

    cell->bit_offset = info->bit_offset;
    cell->nbits = info->nbits;
    @@ -376,13 +374,30 @@ static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
    if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
    dev_err(&nvmem->dev,
    "cell %s unaligned to nvmem stride %d\n",
    - cell->name, nvmem->stride);
    + cell->name ?: "<unknown>", nvmem->stride);
    return -EINVAL;
    }

    return 0;
    }

    +static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
    + const struct nvmem_cell_info *info,
    + struct nvmem_cell *cell)
    +{
    + int err;
    +
    + err = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, cell);
    + if (err)
    + return err;
    +
    + cell->name = kstrdup_const(info->name, GFP_KERNEL);
    + if (!cell->name)
    + return -ENOMEM;
    +
    + return 0;
    +}
    +
    /**
    * nvmem_add_cells() - Add cell information to an nvmem device
    *
    @@ -1436,7 +1451,7 @@ ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
    if (!nvmem)
    return -EINVAL;

    - rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
    + rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
    if (rc)
    return rc;

    @@ -1466,7 +1481,7 @@ int nvmem_device_cell_write(struct nvmem_device *nvmem,
    if (!nvmem)
    return -EINVAL;

    - rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
    + rc = nvmem_cell_info_to_nvmem_cell_nodup(nvmem, info, &cell);
    if (rc)
    return rc;

    --
    2.25.1


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