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Re: [Qemu-ppc] [PATCH 3/3 v2] ppc debug: Add debug stub support

From: Alexander Graf
Subject: Re: [Qemu-ppc] [PATCH 3/3 v2] ppc debug: Add debug stub support
Date: Tue, 17 Jun 2014 13:03:00 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.6.0

On 17.06.14 13:01, address@hidden wrote:
+static void kvm_arch_e500_update_guest_debug(CPUState *cs,
+                                             struct
+*dbg) {
+    int n;
+    if (nb_hw_breakpoint + nb_hw_watchpoint > 0) {
+        dbg->control |= KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_HW_BP;
+        memset(dbg->arch.bp, 0, sizeof(dbg->arch.bp));
+        for (n = 0; n < nb_hw_breakpoint + nb_hw_watchpoint; n++)
+ {
Boundary check against dbg->arch.bp missing.
Did not get, what you mean by " dbg->arch.bp missing" ?
dbg->arch.bp is an array of a certain size. If nb_hw_breakpoint +
nb_hw_watchpoint > ARRAY_SIZE(dbg->arch.bp) we might overwrite memory
we don't want to overwrite.
Actually this will never overflow here because nb_hw_breakpoint and
nb_hw_watchpoint overflow in taken care in in hw_insert_breakpoint().
Do you thing that to be double safe we can add a check?
We only check against an overflow of hw_breakpoint[], not dbg->arch.bp.
What if nb_hw_breakpoint becomes 17?
nb_hw_breakpoint can never be more than max_hw_breakpoint, how nb_hw_breakpoint 
can be 17 ?

Someone comes along and bumps up max_hw_breakpoint to 17? Just add an assert() somewhere that makes sure we can't run over bp :).


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