From c4e22c2bf4c1f2bbd11d12de6c9b0d6cb1a2fb5d Mon Sep 17 00:00:00 2001 From: Jorge Ramirez-Ortiz Date: Sat, 13 Apr 2019 11:32:58 +0100 Subject: [PATCH] nvmem: core: fix read buffer in place [ Upstream commit 2fe518fecb3a4727393be286db9804cd82ee2d91 ] When the bit_offset in the cell is zero, the pointer to the msb will not be properly initialized (ie, will still be pointing to the first byte in the buffer). This being the case, if there are bits to clear in the msb, those will be left untouched while the mask will incorrectly clear bit positions on the first byte. This commit also makes sure that any byte unused in the cell is cleared. Signed-off-by: Jorge Ramirez-Ortiz Signed-off-by: Srinivas Kandagatla Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/nvmem/core.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 635886e4835c..dba3f4d0a63d 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -954,7 +954,7 @@ static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf) { u8 *p, *b; - int i, bit_offset = cell->bit_offset; + int i, extra, bit_offset = cell->bit_offset; p = b = buf; if (bit_offset) { @@ -969,11 +969,16 @@ static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, p = b; *b++ >>= bit_offset; } - - /* result fits in less bytes */ - if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE)) - *p-- = 0; + } else { + /* point to the msb */ + p += cell->bytes - 1; } + + /* result fits in less bytes */ + extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE); + while (--extra >= 0) + *p-- = 0; + /* clear msb bits if any leftover in the last byte */ *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0); } -- 2.20.1