[PATCH 4.17 192/336] nvmem: properly handle returned value nvmem_reg_read

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathieu Malaterre <malat@xxxxxxxxxx>

[ Upstream commit 50808bfcc14b854775a9f1d0abe3dac2babcf5c3 ]

Function nvmem_reg_read can return a non zero value indicating an error.
This returned value must be read and error propagated to
nvmem_cell_prepare_write_buffer. Silence the following gcc warning (W=1):

drivers/nvmem/core.c:1093:9: warning: variable 'rc' set but
 not used [-Wunused-but-set-variable]

Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/nvmem/core.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1107,6 +1107,8 @@ static void *nvmem_cell_prepare_write_bu
 
 		/* setup the first byte with lsb bits from nvmem */
 		rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
+		if (rc)
+			goto err;
 		*b++ |= GENMASK(bit_offset - 1, 0) & v;
 
 		/* setup rest of the byte if any */
@@ -1125,11 +1127,16 @@ static void *nvmem_cell_prepare_write_bu
 		/* setup the last byte with msb bits from nvmem */
 		rc = nvmem_reg_read(nvmem,
 				    cell->offset + cell->bytes - 1, &v, 1);
+		if (rc)
+			goto err;
 		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
 
 	}
 
 	return buf;
+err:
+	kfree(buf);
+	return ERR_PTR(rc);
 }
 
 /**