From 31507fc2ad36e0071751a710449db19c85d82a7f Mon Sep 17 00:00:00 2001 From: Jennifer Berringer Date: Mon, 30 Dec 2024 14:19:01 +0000 Subject: [PATCH] nvmem: core: improve range check for nvmem_cell_write() 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 Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20241230141901.263976-7-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/nvmem/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index fd09f1a6917fe..fff85bbf0ecd0 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -1793,6 +1793,8 @@ 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); -- 2.51.0