rman: fix overflow in rman_reserve_resource_bound()
If the default range of [0, ~0] is given, then (~0 - 0) + 1 == 0. This in turn will cause any allocation of non-zero size to fail. Zero-sized allocations are prohibited, so add a KASSERT to this effect. History indicates it is part of the original rman code. This bug may in fact be older than some contributors. Reviewed by: mhorne MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D30280
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@ -445,6 +445,8 @@ rman_reserve_resource_bound(struct rman *rm, rman_res_t start, rman_res_t end,
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"length %#jx, flags %x, device %s\n", rm->rm_descr, start, end,
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count, flags,
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dev == NULL ? "<null>" : device_get_nameunit(dev)));
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KASSERT(count != 0, ("%s: attempted to allocate an empty range",
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__func__));
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KASSERT((flags & RF_FIRSTSHARE) == 0,
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("invalid flags %#x", flags));
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new_rflags = (flags & ~RF_FIRSTSHARE) | RF_ALLOCATED;
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@ -520,7 +522,7 @@ rman_reserve_resource_bound(struct rman *rm, rman_res_t start, rman_res_t end,
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DPRINTF(("truncated region: [%#jx, %#jx]; size %#jx (requested %#jx)\n",
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rstart, rend, (rend - rstart + 1), count));
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if ((rend - rstart + 1) >= count) {
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if ((rend - rstart) >= (count - 1)) {
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DPRINTF(("candidate region: [%#jx, %#jx], size %#jx\n",
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rstart, rend, (rend - rstart + 1)));
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if ((s->r_end - s->r_start + 1) == count) {
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