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    Subject[PATCH 3.18 009/124] scsi: sd: Fix capacity calculation with 32-bit sector_t
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

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

    From: Martin K. Petersen <martin.petersen@oracle.com>

    commit 7c856152cb92f8eee2df29ef325a1b1f43161aff upstream.

    We previously made sure that the reported disk capacity was less than
    0xffffffff blocks when the kernel was not compiled with large sector_t
    support (CONFIG_LBDAF). However, this check assumed that the capacity
    was reported in units of 512 bytes.

    Add a sanity check function to ensure that we only enable disks if the
    entire reported capacity can be expressed in terms of sector_t.

    Reported-by: Steve Magnani <steve.magnani@digidescorp.com>
    Cc: Bart Van Assche <Bart.VanAssche@sandisk.com>
    Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/scsi/sd.c | 20 ++++++++++++++++++--
    1 file changed, 18 insertions(+), 2 deletions(-)

    --- a/drivers/scsi/sd.c
    +++ b/drivers/scsi/sd.c
    @@ -1979,6 +1979,22 @@ static void read_capacity_error(struct s

    #define READ_CAPACITY_RETRIES_ON_RESET 10

    +/*
    + * Ensure that we don't overflow sector_t when CONFIG_LBDAF is not set
    + * and the reported logical block size is bigger than 512 bytes. Note
    + * that last_sector is a u64 and therefore logical_to_sectors() is not
    + * applicable.
    + */
    +static bool sd_addressable_capacity(u64 lba, unsigned int sector_size)
    +{
    + u64 last_sector = (lba + 1ULL) << (ilog2(sector_size) - 9);
    +
    + if (sizeof(sector_t) == 4 && last_sector > U32_MAX)
    + return false;
    +
    + return true;
    +}
    +
    static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
    unsigned char *buffer)
    {
    @@ -2044,7 +2060,7 @@ static int read_capacity_16(struct scsi_
    return -ENODEV;
    }

    - if ((sizeof(sdkp->capacity) == 4) && (lba >= 0xffffffffULL)) {
    + if (!sd_addressable_capacity(lba, sector_size)) {
    sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "
    "kernel compiled with support for large block "
    "devices.\n");
    @@ -2130,7 +2146,7 @@ static int read_capacity_10(struct scsi_
    return sector_size;
    }

    - if ((sizeof(sdkp->capacity) == 4) && (lba == 0xffffffff)) {
    + if (!sd_addressable_capacity(lba, sector_size)) {
    sd_printk(KERN_ERR, sdkp, "Too big for this kernel. Use a "
    "kernel compiled with support for large block "
    "devices.\n");

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