fixing a few bugs discovered by Coverity

Files: common/acpi.c, include/compiler.h, arch/x86/pagetables.c include/arch/x86/pagetable.h These bugs were discovered and resolved using Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc. Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
KernelTestFramework · Aug 27, 2020 · c83fc4e · c83fc4e
1 parent 9bff053
commit c83fc4e
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Showing 4 changed files with 26 additions and 9 deletions.
diff --git a/arch/x86/pagetables.c b/arch/x86/pagetables.c
@@ -100,10 +100,10 @@ static void *init_map_mfn(mfn_t mfn) {
     static uint8_t _tmp[PAGE_SIZE] __aligned(PAGE_SIZE);
     pgentry_t *e;
 
-    if (mfn_invalid(mfn))
-        return NULL;
+    BUG_ON(mfn_invalid(mfn));
 
     e = (pgentry_t *) l1_table_entry(get_l1_table(_tmp), _tmp);
+    BUG_ON(!e);
     set_pgentry(e, mfn, L1_PROT);
 
     return _tmp;

diff --git a/common/acpi.c b/common/acpi.c
@@ -120,6 +120,9 @@ static inline void *acpi_map_table(paddr_t pa) {
 static inline rsdt_t *acpi_find_rsdt(const rsdp_rev1_t *rsdp) {
     rsdt_t *rsdt = acpi_map_table(rsdp->rsdt_paddr);
 
+    if (!rsdt)
+        return NULL;
+
     if (RSDT_SIGNATURE != rsdt->header.signature)
         return NULL;
 
@@ -132,6 +135,9 @@ static inline rsdt_t *acpi_find_rsdt(const rsdp_rev1_t *rsdp) {
 static inline xsdt_t *acpi_find_xsdt(const rsdp_rev2_t *rsdp) {
     xsdt_t *xsdt = acpi_map_table(rsdp->xsdt_paddr);
 
+    if (!xsdt)
+        return NULL;
+
     if (XSDT_SIGNATURE != xsdt->header.signature)
         return NULL;
 
@@ -158,6 +164,9 @@ static unsigned process_madt_entries(void) {
     acpi_madt_t *madt = (acpi_madt_t *) acpi_find_table(MADT_SIGNATURE);
     acpi_madt_entry_t *entry;
 
+    if (!madt)
+        return 0;
+
     printk("ACPI: [MADT] LAPIC Addr: %p, Flags: %08x\n", _ptr(madt->lapic_addr),
            madt->flags);
 
@@ -219,21 +228,27 @@ void init_acpi(void) {
     if (rsdp->rev < 2) {
         rsdt_t *rsdt = acpi_find_rsdt(rsdp);
 
+        if (!rsdt)
+            return;
+
         for (unsigned int i = 0; i < ACPI_NR_TABLES(rsdt); i++) {
             acpi_table_t *tab = acpi_map_table(rsdt->entry[i]);
 
-            if (get_checksum(tab, tab->header.length) == 0x0)
+            if (tab && get_checksum(tab, tab->header.length) == 0x0)
                 acpi_tables[max_acpi_tables++] = tab;
         }
     }
     else {
         xsdt_t *xsdt = acpi_find_xsdt((rsdp_rev2_t *) rsdp);
 
+        if (!xsdt)
+            return;
+
         for (unsigned int i = 0; i < ACPI_NR_TABLES(xsdt); i++) {
             paddr_t tab_pa = _ul(xsdt->entry[i].high) << 32 | xsdt->entry[i].low;
             acpi_table_t *tab = acpi_map_table(tab_pa);
 
-            if (get_checksum(tab, tab->header.length) == 0x0)
+            if (tab && get_checksum(tab, tab->header.length) == 0x0)
                 acpi_tables[max_acpi_tables++] = tab;
         }
     }

diff --git a/include/arch/x86/pagetable.h b/include/arch/x86/pagetable.h
@@ -212,13 +212,15 @@ static inline pgentry_t pgentry_from_virt(const void *va, unsigned long flags) {
     return pgentry_from_paddr(virt_to_paddr(va), flags);
 }
 
+#define INVALID_PGENTRY(e) (!(e) || mfn_invalid((e)->mfn))
+
 #if defined(__x86_64__)
 static inline pml4_t *get_l4_table(void) { return paddr_to_virt_kern(read_cr3()); }
 
 static inline pdpe_t *get_l3_table(const void *va) {
     pml4_t *l3e = l4_table_entry(get_l4_table(), va);
 
-    return mfn_invalid(l3e->mfn) ? NULL : mfn_to_virt_kern(l3e->mfn);
+    return INVALID_PGENTRY(l3e) ? NULL : mfn_to_virt_kern(l3e->mfn);
 }
 #elif defined(__i386__)
 static inline pdpe_t *get_l3_table(void) { return paddr_to_virt_kern(read_cr3()); }
@@ -227,13 +229,13 @@ static inline pdpe_t *get_l3_table(void) { return paddr_to_virt_kern(read_cr3())
 static inline pde_t *get_l2_table(const void *va) {
     pdpe_t *l2e = l3_table_entry(get_l3_table(va), va);
 
-    return mfn_invalid(l2e->mfn) ? NULL : mfn_to_virt_kern(l2e->mfn);
+    return INVALID_PGENTRY(l2e) ? NULL : mfn_to_virt_kern(l2e->mfn);
 }
 
 static inline pte_t *get_l1_table(const void *va) {
     pde_t *l1e = l2_table_entry(get_l2_table(va), va);
 
-    return mfn_invalid(l1e->mfn) ? NULL : mfn_to_virt_kern(l1e->mfn);
+    return INVALID_PGENTRY(l1e) ? NULL : mfn_to_virt_kern(l1e->mfn);
 }
 
 static inline void set_pgentry(pgentry_t *e, mfn_t mfn, unsigned long flags) {

diff --git a/include/compiler.h b/include/compiler.h
@@ -72,8 +72,8 @@
 #define __bss_init  __section(".bss.init")
 
 #define IS_INIT_SECTION(name)                                                            \
-    (!strcmp(name, ".text.init") || !strcmp(name, ".data.init") ||                       \
-     !strcmp(name, ".bss.init"))
+    ((name) && (!strcmp(name, ".text.init") || !strcmp(name, ".data.init") ||            \
+                !strcmp(name, ".bss.init")))
 
 #define __user_text __section(".text.user")
 #define __user_data __section(".data.user")