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    Subject[PATCH] blktrace: fix a bug in blk_msg_write()
    This is another long-standing bug.


    ================


    (console 1)
    # echo -n 'a' > /sys/kernel/debug/block/sda/msg
    (console 2)
    # blktrace -d /dev/sda -a pc -o - | blkparse -i -
    8,0 0 0 0.000000000 0 m N a������@��

    We should terminate the msg buffer with '\0'.

    Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
    ---
    kernel/trace/blktrace.c | 5 +++--
    1 files changed, 3 insertions(+), 2 deletions(-)

    diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
    index c0ef70d..2bf341f 100644
    --- a/kernel/trace/blktrace.c
    +++ b/kernel/trace/blktrace.c
    @@ -327,10 +327,10 @@ static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
    char *msg;
    struct blk_trace *bt;

    - if (count > BLK_TN_MAX_MSG)
    + if (count >= BLK_TN_MAX_MSG)
    return -EINVAL;

    - msg = kmalloc(count, GFP_KERNEL);
    + msg = kmalloc(count + 1, GFP_KERNEL);
    if (msg == NULL)
    return -ENOMEM;

    @@ -338,6 +338,7 @@ static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
    kfree(msg);
    return -EFAULT;
    }
    + msg[count] = '\0';

    bt = filp->private_data;
    __trace_note_message(bt, "%s", msg);
    --
    1.5.4.rc3

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