Prior to commit 5d8e6e6c10a3 ("nvmem: core: add an index parameter to
the cell") of_nvmem_cell_get() would return -ENOENT if the cell wasn't
found. Particularly, if of_property_match_string() returned -EINVAL,
that return code was passed as the index to of_parse_phandle(), which
then detected it as invalid and returned NULL. That led to an return
code of -ENOENT.

With the new code, the negative index will lead to an -EINVAL of
of_parse_phandle_with_optional_args() which pass straight to the
caller and break those who expect an -ENOENT.

Fix it by always returning -ENOENT.

Fixes: 5d8e6e6c10a3 ("nvmem: core: add an index parameter to the cell")
Reported-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Link: https://lore.kernel.org/r/2143916.GUh0CODmnK@steina-w/
Signed-off-by: Michael Walle <michael@walle.cc>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
---
Updated the commit ids as they are in Linus' tree. Added the link
to the report.

 drivers/nvmem/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 174ef3574e07..22024b830788 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1231,7 +1231,7 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
 						  "#nvmem-cell-cells",
 						  index, &cell_spec);
 	if (ret)
-		return ERR_PTR(ret);
+		return ERR_PTR(-ENOENT);
 
 	if (cell_spec.args_count > 1)
 		return ERR_PTR(-EINVAL);
-- 
2.30.2

On 27/02/2023 08:52, Michael Walle wrote:
> Prior to commit 5d8e6e6c10a3 ("nvmem: core: add an index parameter to
> the cell") of_nvmem_cell_get() would return -ENOENT if the cell wasn't
> found. Particularly, if of_property_match_string() returned -EINVAL,
> that return code was passed as the index to of_parse_phandle(), which
> then detected it as invalid and returned NULL. That led to an return
> code of -ENOENT.
> 
> With the new code, the negative index will lead to an -EINVAL of
> of_parse_phandle_with_optional_args() which pass straight to the
> caller and break those who expect an -ENOENT.
> 
> Fix it by always returning -ENOENT.
> 
> Fixes: 5d8e6e6c10a3 ("nvmem: core: add an index parameter to the cell")
> Reported-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> Link: https://lore.kernel.org/r/2143916.GUh0CODmnK@steina-w/
> Signed-off-by: Michael Walle <michael@walle.cc>
> Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> ---

Applied thanks,

--srini
> Updated the commit ids as they are in Linus' tree. Added the link
> to the report.
> 
>   drivers/nvmem/core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index 174ef3574e07..22024b830788 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -1231,7 +1231,7 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
>   						  "#nvmem-cell-cells",
>   						  index, &cell_spec);
>   	if (ret)
> -		return ERR_PTR(ret);
> +		return ERR_PTR(-ENOENT);
>   
>   	if (cell_spec.args_count > 1)
>   		return ERR_PTR(-EINVAL);