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    Subject[PATCH 4.9 59/91] bcache: fix input overflow to sequential_cutoff
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

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

    [ Upstream commit 8c27a3953e92eb0b22dbb03d599f543a05f9574e ]

    People may set sequential_cutoff of a cached device via sysfs file,
    but current code does not check input value overflow. E.g. if value
    4294967295 (UINT_MAX) is written to file sequential_cutoff, its value
    is 4GB, but if 4294967296 (UINT_MAX + 1) is written into, its value
    will be 0. This is an unexpected behavior.

    This patch replaces d_strtoi_h() by sysfs_strtoul_clamp() to convert
    input string to unsigned integer value, and limit its range in
    [0, UINT_MAX]. Then the input overflow can be fixed.

    Signed-off-by: Coly Li <colyli@suse.de>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/md/bcache/sysfs.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
    index 87daccbbc61b..463ce6757338 100644
    --- a/drivers/md/bcache/sysfs.c
    +++ b/drivers/md/bcache/sysfs.c
    @@ -215,7 +215,9 @@ STORE(__cached_dev)
    d_strtoul(writeback_rate_d_term);
    d_strtoul_nonzero(writeback_rate_p_term_inverse);

    - d_strtoi_h(sequential_cutoff);
    + sysfs_strtoul_clamp(sequential_cutoff,
    + dc->sequential_cutoff,
    + 0, UINT_MAX);
    d_strtoi_h(readahead);

    if (attr == &sysfs_clear_stats)
    --
    2.19.1


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