[PATCH v3 2/5] lib: utils/irqchip: plic: Ensure no out-of-bound access in priority save/restore helpers

[Bin Meng]

Currently the priority save/restore helpers writes/reads the provided
array using an index whose maximum value is determined by PLIC, which
potentially may disagree with the caller to these helpers.

Add a parameter to ask the caller to provide the size limit of the
array to ensure no out-of-bound access happens.

Signed-off-by: Bin Meng <bmeng at tinylab.org>

---

Changes in v3:
- fix the size limit check
- move the size limit check to plic_priority_save/restore
- add parameter description to fdt_plic_priority_save/restore

Changes in v2:
- new patch: libs: utils/irqchip: plic: Ensure no out-of-bound access in priority save/restore helpers

 include/sbi_utils/irqchip/fdt_irqchip_plic.h | 14 ++++++++++++--
 include/sbi_utils/irqchip/plic.h             |  5 +++--
 lib/utils/irqchip/fdt_irqchip_plic.c         |  8 ++++----
 lib/utils/irqchip/plic.c                     | 15 +++++++++++----
 platform/generic/allwinner/sun20i-d1.c       |  4 ++--
 5 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/include/sbi_utils/irqchip/fdt_irqchip_plic.h b/include/sbi_utils/irqchip/fdt_irqchip_plic.h
index 98d4de5..d5b1c60 100644
--- a/include/sbi_utils/irqchip/fdt_irqchip_plic.h
+++ b/include/sbi_utils/irqchip/fdt_irqchip_plic.h
@@ -9,9 +9,19 @@
 
 #include <sbi/sbi_types.h>
 
-void fdt_plic_priority_save(u8 *priority);
+/**
+ * Save the PLIC priority state
+ * @param priority pointer to the memory region for the saved priority
+ * @param num size of the memory region including interrupt source 0
+ */
+void fdt_plic_priority_save(u8 *priority, u32 num);
 
-void fdt_plic_priority_restore(const u8 *priority);
+/**
+ * Restore the PLIC priority state
+ * @param priority pointer to the memory region for the saved priority
+ * @param num size of the memory region including interrupt source 0
+ */
+void fdt_plic_priority_restore(const u8 *priority, u32 num);
 
 void fdt_plic_context_save(bool smode, u32 *enable, u32 *threshold);
 
diff --git a/include/sbi_utils/irqchip/plic.h b/include/sbi_utils/irqchip/plic.h
index 48c24f0..38704a1 100644
--- a/include/sbi_utils/irqchip/plic.h
+++ b/include/sbi_utils/irqchip/plic.h
@@ -18,9 +18,10 @@ struct plic_data {
 };
 
 /* So far, priorities on all consumers of these functions fit in 8 bits. */
-void plic_priority_save(const struct plic_data *plic, u8 *priority);
+void plic_priority_save(const struct plic_data *plic, u8 *priority, u32 num);
 
-void plic_priority_restore(const struct plic_data *plic, const u8 *priority);
+void plic_priority_restore(const struct plic_data *plic, const u8 *priority,
+			   u32 num);
 
 void plic_context_save(const struct plic_data *plic, int context_id,
 		       u32 *enable, u32 *threshold);
diff --git a/lib/utils/irqchip/fdt_irqchip_plic.c b/lib/utils/irqchip/fdt_irqchip_plic.c
index fe08836..7d76c5b 100644
--- a/lib/utils/irqchip/fdt_irqchip_plic.c
+++ b/lib/utils/irqchip/fdt_irqchip_plic.c
@@ -24,18 +24,18 @@ static struct plic_data plic[PLIC_MAX_NR];
 static struct plic_data *plic_hartid2data[SBI_HARTMASK_MAX_BITS];
 static int plic_hartid2context[SBI_HARTMASK_MAX_BITS][2];
 
-void fdt_plic_priority_save(u8 *priority)
+void fdt_plic_priority_save(u8 *priority, u32 num)
 {
 	struct plic_data *plic = plic_hartid2data[current_hartid()];
 
-	plic_priority_save(plic, priority);
+	plic_priority_save(plic, priority, num);
 }
 
-void fdt_plic_priority_restore(const u8 *priority)
+void fdt_plic_priority_restore(const u8 *priority, u32 num)
 {
 	struct plic_data *plic = plic_hartid2data[current_hartid()];
 
-	plic_priority_restore(plic, priority);
+	plic_priority_restore(plic, priority, num);
 }
 
 void fdt_plic_context_save(bool smode, u32 *enable, u32 *threshold)
diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c
index 4df9020..dca5678 100644
--- a/lib/utils/irqchip/plic.c
+++ b/lib/utils/irqchip/plic.c
@@ -36,15 +36,22 @@ static void plic_set_priority(const struct plic_data *plic, u32 source, u32 val)
 	writel(val, plic_priority);
 }
 
-void plic_priority_save(const struct plic_data *plic, u8 *priority)
+void plic_priority_save(const struct plic_data *plic, u8 *priority, u32 num)
 {
-	for (u32 i = 1; i <= plic->num_src; i++)
+	if (num > plic->num_src)
+		num = plic->num_src;
+
+	for (u32 i = 1; i <= num; i++)
 		priority[i] = plic_get_priority(plic, i);
 }
 
-void plic_priority_restore(const struct plic_data *plic, const u8 *priority)
+void plic_priority_restore(const struct plic_data *plic, const u8 *priority,
+			   u32 num)
 {
-	for (u32 i = 1; i <= plic->num_src; i++)
+	if (num > plic->num_src)
+		num = plic->num_src;
+
+	for (u32 i = 1; i <= num; i++)
 		plic_set_priority(plic, i, priority[i]);
 }
 
diff --git a/platform/generic/allwinner/sun20i-d1.c b/platform/generic/allwinner/sun20i-d1.c
index 18d330d..1f27575 100644
--- a/platform/generic/allwinner/sun20i-d1.c
+++ b/platform/generic/allwinner/sun20i-d1.c
@@ -79,13 +79,13 @@ static u32 plic_threshold;
 static void sun20i_d1_plic_save(void)
 {
 	fdt_plic_context_save(true, plic_sie, &plic_threshold);
-	fdt_plic_priority_save(plic_priority);
+	fdt_plic_priority_save(plic_priority, PLIC_SOURCES);
 }
 
 static void sun20i_d1_plic_restore(void)
 {
 	thead_plic_restore();
-	fdt_plic_priority_restore(plic_priority);
+	fdt_plic_priority_restore(plic_priority, PLIC_SOURCES);
 	fdt_plic_context_restore(true, plic_sie, plic_threshold);
 }
 
-- 
2.34.1