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exec.c: Don't reallocate IOMMUNotifiers that are in use 

The tcg_register_iommu_notifier() code has a GArray of
TCGIOMMUNotifier structs which it has registered by passing
memory_region_register_iommu_notifier() a pointer to the embedded
IOMMUNotifier field. Unfortunately, if we need to enlarge the
array via g_array_set_size() this can cause a realloc(), which
invalidates the pointer that memory_region_register_iommu_notifier()
put into the MemoryRegion's iommu_notify list. This can result
in segfaults.

Switch the GArray to holding pointers to the TCGIOMMUNotifier
structs, so that we can individually allocate and free them.

Cc: qemu-stable@nongnu.org
Fixes: 1f871c5e6b ("exec.c: Handle IOMMUs in address_space_translate_for_iotlb()")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190128174241.5860-1-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2019-02-01 14:55:45 +00:00
parent 4977986ca3
commit 5601be3b01
1 changed files with 6 additions and 4 deletions
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10
exec.c
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@ -665,7 +665,7 @@ static void tcg_register_iommu_notifier(CPUState *cpu,
int i;
for (i = 0; i < cpu->iommu_notifiers->len; i++) {
notifier = &g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier, i);
notifier = g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier *, i);
if (notifier->mr == mr && notifier->iommu_idx == iommu_idx) {
break;
}
@ -673,7 +673,8 @@ static void tcg_register_iommu_notifier(CPUState *cpu,
if (i == cpu->iommu_notifiers->len) {
/* Not found, add a new entry at the end of the array */
cpu->iommu_notifiers = g_array_set_size(cpu->iommu_notifiers, i + 1);
notifier = &g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier, i);
notifier = g_new0(TCGIOMMUNotifier, 1);
g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier *, i) = notifier;
notifier->mr = mr;
notifier->iommu_idx = iommu_idx;
@ -705,8 +706,9 @@ static void tcg_iommu_free_notifier_list(CPUState *cpu)
TCGIOMMUNotifier *notifier;
for (i = 0; i < cpu->iommu_notifiers->len; i++) {
notifier = &g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier, i);
notifier = g_array_index(cpu->iommu_notifiers, TCGIOMMUNotifier *, i);
memory_region_unregister_iommu_notifier(notifier->mr, &notifier->n);
g_free(notifier);
}
g_array_free(cpu->iommu_notifiers, true);
}
@ -976,7 +978,7 @@ void cpu_exec_realizefn(CPUState *cpu, Error **errp)
vmstate_register(NULL, cpu->cpu_index, cc->vmsd, cpu);
}
cpu->iommu_notifiers = g_array_new(false, true, sizeof(TCGIOMMUNotifier));
cpu->iommu_notifiers = g_array_new(false, true, sizeof(TCGIOMMUNotifier *));
#endif
}