journald: add some additional checks before we divide by values read from journal...

Since the file headers might be replaced by zeroed pages now due to
sigbus we should make sure we don't end up dividing by zero because we
don't check values read from journal file headers for changes.

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 44a96928e027dade0b915054fecaf8c0c1d63b1b..1736ff57af795b08b69cf4a943f1c4278061fd6c 100644 (file)
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -658,7 +658,7 @@ static int journal_file_link_field(
                 uint64_t offset,
                 uint64_t hash) {
 
-        uint64_t p, h;
+        uint64_t p, h, m;
         int r;
 
         assert(f);
@@ -668,11 +668,14 @@ static int journal_file_link_field(
         if (o->object.type != OBJECT_FIELD)
                 return -EINVAL;
 
-        /* This might alter the window we are looking at */
+        m = le64toh(f->header->field_hash_table_size) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
 
+        /* This might alter the window we are looking at */
         o->field.next_hash_offset = o->field.head_data_offset = 0;
 
-        h = hash % (le64toh(f->header->field_hash_table_size) / sizeof(HashItem));
+        h = hash % m;
         p = le64toh(f->field_hash_table[h].tail_hash_offset);
         if (p == 0)
                 f->field_hash_table[h].head_hash_offset = htole64(offset);
@@ -698,7 +701,7 @@ static int journal_file_link_data(
                 uint64_t offset,
                 uint64_t hash) {
 
-        uint64_t p, h;
+        uint64_t p, h, m;
         int r;
 
         assert(f);
@@ -708,13 +711,16 @@ static int journal_file_link_data(
         if (o->object.type != OBJECT_DATA)
                 return -EINVAL;
 
-        /* This might alter the window we are looking at */
+        m = le64toh(f->header->data_hash_table_size) / sizeof(HashItem);
+        if (m <= 0)
+                return -EBADMSG;
 
+        /* This might alter the window we are looking at */
         o->data.next_hash_offset = o->data.next_field_offset = 0;
         o->data.entry_offset = o->data.entry_array_offset = 0;
         o->data.n_entries = 0;
 
-        h = hash % (le64toh(f->header->data_hash_table_size) / sizeof(HashItem));
+        h = hash % m;
         p = le64toh(f->data_hash_table[h].tail_hash_offset);
         if (p == 0)
                 /* Only entry in the hash table is easy */
@@ -743,7 +749,7 @@ int journal_file_find_field_object_with_hash(
                 const void *field, uint64_t size, uint64_t hash,
                 Object **ret, uint64_t *offset) {
 
-        uint64_t p, osize, h;
+        uint64_t p, osize, h, m;
         int r;
 
         assert(f);
@@ -751,10 +757,12 @@ int journal_file_find_field_object_with_hash(
 
         osize = offsetof(Object, field.payload) + size;
 
-        if (f->header->field_hash_table_size == 0)
+        m = le64toh(f->header->field_hash_table_size) / sizeof(HashItem);
+
+        if (m <= 0)
                 return -EBADMSG;
 
-        h = hash % (le64toh(f->header->field_hash_table_size) / sizeof(HashItem));
+        h = hash % m;
         p = le64toh(f->field_hash_table[h].head_hash_offset);
 
         while (p > 0) {
@@ -804,7 +812,7 @@ int journal_file_find_data_object_with_hash(
                 const void *data, uint64_t size, uint64_t hash,
                 Object **ret, uint64_t *offset) {
 
-        uint64_t p, osize, h;
+        uint64_t p, osize, h, m;
         int r;
 
         assert(f);
@@ -812,10 +820,11 @@ int journal_file_find_data_object_with_hash(
 
         osize = offsetof(Object, data.payload) + size;
 
-        if (f->header->data_hash_table_size == 0)
+        m = le64toh(f->header->data_hash_table_size) / sizeof(HashItem);
+        if (m <= 0)
                 return -EBADMSG;
 
-        h = hash % (le64toh(f->header->data_hash_table_size) / sizeof(HashItem));
+        h = hash % m;
         p = le64toh(f->data_hash_table[h].head_hash_offset);
 
         while (p > 0) {