5.4-stable review patch. If anyone has any objections, please let me know.
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From: Jennifer Berringer jberring@redhat.com
commit 31507fc2ad36e0071751a710449db19c85d82a7f upstream.
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@vger.kernel.org Signed-off-by: Jennifer Berringer jberring@redhat.com Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org Link: https://lore.kernel.org/r/20241230141901.263976-7-srinivas.kandagatla@linaro... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/nvmem/core.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -1083,6 +1083,8 @@ int nvmem_cell_write(struct nvmem_cell * 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);