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    Subject[PATCH 5.4 106/240] random: round-robin registers as ulong, not u32
    Date
    From: "Jason A. Donenfeld" <Jason@zx2c4.com>

    commit da3951ebdcd1cb1d5c750e08cd05aee7b0c04d9a upstream.

    When the interrupt handler does not have a valid cycle counter, it calls
    get_reg() to read a register from the irq stack, in round-robin.
    Currently it does this assuming that registers are 32-bit. This is
    _probably_ the case, and probably all platforms without cycle counters
    are in fact 32-bit platforms. But maybe not, and either way, it's not
    quite correct. This commit fixes that to deal with `unsigned long`
    rather than `u32`.

    Cc: Theodore Ts'o <tytso@mit.edu>
    Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
    Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/char/random.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- a/drivers/char/random.c
    +++ b/drivers/char/random.c
    @@ -1256,15 +1256,15 @@ int random_online_cpu(unsigned int cpu)
    }
    #endif

    -static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
    +static unsigned long get_reg(struct fast_pool *f, struct pt_regs *regs)
    {
    - u32 *ptr = (u32 *)regs;
    + unsigned long *ptr = (unsigned long *)regs;
    unsigned int idx;

    if (regs == NULL)
    return 0;
    idx = READ_ONCE(f->reg_idx);
    - if (idx >= sizeof(struct pt_regs) / sizeof(u32))
    + if (idx >= sizeof(struct pt_regs) / sizeof(unsigned long))
    idx = 0;
    ptr += idx++;
    WRITE_ONCE(f->reg_idx, idx);

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