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    Subject[PATCH 3.19.y-ckt 036/155] regmap: debugfs: Ensure we don't underflow when printing access masks
    Date
    3.19.8-ckt10 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Mark Brown <broonie@kernel.org>

    commit b763ec17ac762470eec5be8ebcc43e4f8b2c2b82 upstream.

    If a read is attempted which is smaller than the line length then we may
    underflow the subtraction we're doing with the unsigned size_t type so
    move some of the calculation to be additions on the right hand side
    instead in order to avoid this.

    Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
    Signed-off-by: Mark Brown <broonie@kernel.org>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/base/regmap/regmap-debugfs.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
    index 5799a0b..1f6cd15 100644
    --- a/drivers/base/regmap/regmap-debugfs.c
    +++ b/drivers/base/regmap/regmap-debugfs.c
    @@ -432,7 +432,7 @@ static ssize_t regmap_access_read_file(struct file *file,
    /* If we're in the region the user is trying to read */
    if (p >= *ppos) {
    /* ...but not beyond it */
    - if (buf_pos >= count - 1 - tot_len)
    + if (buf_pos + tot_len + 1 >= count)
    break;

    /* Format the register */
    --
    1.9.1


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