Coverity: irdma_reg_user_mr(): Integer handling issues

Subject: Coverity: irdma_reg_user_mr(): Integer handling issues

Hello!

This is an experimental semi-automated report about issues detected by Coverity from a scan of next-20210608 as part of the linux-next scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified lines of code (noted below) that were touched by commits:

Wed Jun 2 19:55:18 2021 -0300
b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")

Coverity reported the following:

*** CID 1505149: Integer handling issues (DIVIDE_BY_ZERO) /drivers/infiniband/hw/irdma/verbs.c: 2794 in irdma_reg_user_mr()
2788 SZ_4K | SZ_2M |
SZ_1G,

2789     							 virt);
2790     	iwmr->len = region->length;
2791     	iwpbl->user_base = virt;
2792     	palloc = &iwpbl->pble_alloc;
2793     	iwmr->type = req.reg_type;

vvv CID 1505149: Integer handling issues (DIVIDE_BY_ZERO)
vvv In function call "ib_umem_num_dma_blocks", division by expression "iwmr-

Quoted 1 line

page_size" which may be zero has undefined behavior.

2794 iwmr->page_cnt = ib_umem_num_dma_blocks(region, iwmr-

Quoted 1 line

page_size);

2795

2796     	switch (req.reg_type) {
2797     	case IRDMA_MEMREG_TYPE_QP:
2798     		use_pbles = ((req.sq_pages + req.rq_pages) > 2);
2799     		err = irdma_handle_q_mem(iwdev, &req, iwpbl,

use_pbles);

If this is a false positive, please let us know so we can mark it as such, or teach the Coverity rules to be smarter. If not, please make sure fixes get into linux-next. :) For patches fixing this, please include these lines (but double-check the "Fixes" first):

Reported-by coverity-bot <[email protected]>

Addresses-Coverity-ID: 1505149 ("Integer handling issues")

Fixes b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")

Thanks for your attention!