RDMA/bnxt_re: fix a size calculation

This is from static analysis not from testing.  Depending on the value
of rcfw->cmdq_depth, then this might not cause an issue at runtime.

The BITS_TO_LONGS() macro tells us how many longs it take to hold a
bitmap.  In other words, it divides by the number if bits per long and
rounds up.  Then we want to take that number and multiple by
sizeof(long) to get the number of bytes to allocate.

The code here does the multiplication first so the rounding up is done
in the wrong place.  So imagine we want to allocate 1 bit, then
"(1 * 8) / 64 = 1" when we round up.  But it should be
"(1 / 64) * 8 = 8".  In other words, because of the rounding difference
we might allocate up to "sizeof(long) - 1" bytes fewer than intended.

Fixes: 1ac5a4047975 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-By: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
index 326805461265f825d58f9d5ec5d306904076ec18..742346ea5b0d1a727f695dc8767a422720a61e2c 100644 (file)
--- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
+++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
@@ -684,8 +684,7 @@ int bnxt_qplib_enable_rcfw_channel(struct pci_dev *pdev,
        /* General */
        rcfw->seq_num = 0;
        set_bit(FIRMWARE_FIRST_FLAG, &rcfw->flags);
-       bmap_size = BITS_TO_LONGS(rcfw->cmdq_depth *
-                                 sizeof(unsigned long));
+       bmap_size = BITS_TO_LONGS(rcfw->cmdq_depth) * sizeof(unsigned long);
        rcfw->cmdq_bitmap = kzalloc(bmap_size, GFP_KERNEL);
        if (!rcfw->cmdq_bitmap)
                return -ENOMEM;