[PATCH v2] nvmem: core: fix possibly memleak when use nvmem_cell_info_to_nvmem_cell()

[Vadym Kochan]

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}. This is fixed by simply
       re-using info->name instead of duplicating it:

           cell->name = info->name

Because cell->name is not used except for error message printing in case
of un-aligned access, the new __nvmem_cell_info_to_nvmem_cell() helper
was introduced.

Fixes: e2a5402ec7c6 ("nvmem: Add nvmem_device based consumer apis.")
Signed-off-by: Vadym Kochan <vadym.koc...@plvision.eu>
---
v2:
    * remove not needed 'kfree_const(cell->name)' after 
nvmem_cell_info_to_nvmem_cell()
      failed.

 drivers/nvmem/core.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 6cd3edb2eaf6..e6d1bc414faf 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -361,16 +361,15 @@ 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(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;
@@ -382,13 +381,31 @@ 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(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
  *
@@ -1460,7 +1477,7 @@ 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(nvmem, info, &cell);
        if (rc)
                return rc;
 
@@ -1490,7 +1507,7 @@ 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(nvmem, info, &cell);
        if (rc)
                return rc;
 
-- 
2.17.1