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base-foc: explicit array-index bounds check

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Adding an explicit check clarifies at the first glance that the array
bounds are respected without needing knowledge about MAX_CAPS_PER_MSG
and L4_UTCB_GENERIC_DATA_SIZE (used for dimensioning 'mr').
This commit is contained in:
Norman Feske 2020-01-07 17:07:57 +01:00 committed by Christian Helmuth
parent 9ec66f0594
commit 01713c74f9
1 changed files with 5 additions and 0 deletions
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repos/base-foc/src/lib/base/ipc.cc
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@ -238,6 +238,11 @@ static l4_msgtag_t copy_msgbuf_to_utcb(Msgbuf_base &snd_msg,
/* setup flexpage for valid capability to delegate */
if (caps[i].valid) {
unsigned const idx = num_msg_words + 2*num_cap_sel;
/* check bounds of 'l4_msg_regs_t::mr' */
if (idx + 1 >= L4_UTCB_GENERIC_DATA_SIZE)
break;
l4_utcb_mr()->mr[idx] = L4_ITEM_MAP/* | L4_ITEM_CONT*/;
l4_utcb_mr()->mr[idx + 1] = l4_obj_fpage(caps[i].sel,
0, L4_FPAGE_RWX).raw;