From: Jennifer Berringer <jberring@xxxxxxxxxx>
When __nvmem_cell_entry_write() is called for an nvmem cell that does
not need bit shifting, it requires that the len parameter exactly
matches the nvmem cell size. However, when the nvmem cell has a nonzero
bit_offset, it was skipping this check.
Accepting values of len larger than the cell size results in
nvmem_cell_prepare_write_buffer() trying to write past the end of a heap
buffer that it allocates. Add a check to avoid that problem and instead
return -EINVAL when len doesn't match the number of bits expected by the
nvmem cell when bit_offset is nonzero.
This check uses cell->nbits in order to allow providing the smaller size
to cells that are shifted into another byte by bit_offset. For example,
a cell with nbits=8 and nonzero bit_offset would have bytes=2 but should
accept a 1-byte write here, although no current callers depend on this.
Fixes: 69aba7948cbe ("nvmem: Add a simple NVMEM framework for consumers")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Jennifer Berringer <jberring@xxxxxxxxxx>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
drivers/nvmem/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index d6494dfc20a7..845540b57e68 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1790,6 +1790,8 @@ static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, si
return -EINVAL;
if (cell->bit_offset || cell->nbits) {
+ if (len != BITS_TO_BYTES(cell->nbits) && len != cell->bytes)
+ return -EINVAL;
buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
if (IS_ERR(buf))
return PTR_ERR(buf);
--
2.25.1
