[PATCH] scsi: osst: silence underflow warning in osst_verify_frame()

[Dan Carpenter]

The code looks like this:

        i = ntohl(aux->filemark_cnt);
        if (STp->header_cache != NULL && i < OS_FM_TAB_MAX && (i > 
STp->filemark_cnt ||
            STp->first_frame_position - 1 != 
ntohl(STp->header_cache->dat_fm_tab.fm_tab_ent[i]))) {

If i is negative then it's less than OS_FM_TAB_MAX so we read before
the start of the STp->header_cache->dat_fm_tab.fm_tab_ent[] array.

Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
---
There is a second static checker warning that I didn't know how to
address:

    drivers/scsi/osst.c:723 osst_verify_frame()
    warn: potential integer overflow from user 'blk_cnt * blk_sz'

diff --git a/drivers/scsi/osst.c b/drivers/scsi/osst.c
index 97ab5f160bc6..2db87ec04f48 100644
--- a/drivers/scsi/osst.c
+++ b/drivers/scsi/osst.c
@@ -619,7 +619,7 @@ static int osst_verify_frame(struct osst_tape * STp, int 
frame_seq_number, int q
        os_aux_t           * aux  = STp->buffer->aux;
        os_partition_t     * par  = &(aux->partition);
        struct st_partstat * STps = &(STp->ps[STp->partition]);
-       int                  blk_cnt, blk_sz, i;
+       unsigned int         blk_cnt, blk_sz, i;
 
        if (STp->raw) {
                if (STp->buffer->syscall_result) {