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nvmem: core: fix read buffer in place

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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 <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jorge Ramirez-Ortiz 2019-04-13 11:32:58 +01:00 committed by Greg Kroah-Hartman
parent 0a9b2d1ce4
commit 2fe518fecb
1 changed files with 10 additions and 5 deletions
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15
drivers/nvmem/core.c
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@ -1166,7 +1166,7 @@ EXPORT_SYMBOL_GPL(nvmem_cell_put);
static 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) {
@ -1181,11 +1181,16 @@ static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
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);
}