tdb: be more careful on 4G files.

I came across a tdb which had wrapped to 4G + 4K, and the contents had been
destroyed by processes which thought it only 4k long.  Fix this by checking
on open, and making tdb_oob() check for wrap itself.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Autobuild-User: Rusty Russell <rusty@rustcorp.com.au>
Autobuild-Date: Mon Dec 19 07:52:01 CET 2011 on sn-devel-104

6 files changed, 53 insertions, 23 deletions

diff --git a/lib/tdb/common/check.c b/lib/tdb/common/check.c
index 3387fbd098..313f55cbb0 100644
--- a/lib/tdb/common/check.c
+++ b/lib/tdb/common/check.c
@@ -92,7 +92,7 @@ static bool tdb_check_record(struct tdb_context *tdb,
 			 off, rec->next));
 		goto corrupt;
 	}
-	if (tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0))
+	if (tdb->methods->tdb_oob(tdb, rec->next, sizeof(*rec), 0))
 		goto corrupt;
 
 	/* Check rec_len: similar to rec->next, implies next record. */
@@ -110,7 +110,7 @@ static bool tdb_check_record(struct tdb_context *tdb,
 		goto corrupt;
 	}
 	/* OOB allows "right at the end" access, so this works for last rec. */
-	if (tdb->methods->tdb_oob(tdb, off+sizeof(*rec)+rec->rec_len, 0))
+	if (tdb->methods->tdb_oob(tdb, off, sizeof(*rec)+rec->rec_len, 0))
 		goto corrupt;
 
 	/* Check tailer. */
@@ -345,7 +345,7 @@ _PUBLIC_ int tdb_check(struct tdb_context *tdb,
 	}
 
 	/* Make sure we know true size of the underlying file. */
-	tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
+	tdb->methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 
 	/* Header must be OK: also gets us the recovery ptr, if any. */
 	if (!tdb_check_header(tdb, &recovery_start))
diff --git a/lib/tdb/common/freelist.c b/lib/tdb/common/freelist.c
index 927078a7aa..6358f64a04 100644
--- a/lib/tdb/common/freelist.c
+++ b/lib/tdb/common/freelist.c
@@ -56,7 +56,7 @@ int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off, struct tdb_record
 			   rec->magic, off));
 		return -1;
 	}
-	if (tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0) != 0)
+	if (tdb->methods->tdb_oob(tdb, rec->next, sizeof(*rec), 0) != 0)
 		return -1;
 	return 0;
 }
diff --git a/lib/tdb/common/io.c b/lib/tdb/common/io.c
index 78bbf2ec77..a2db3bf4bd 100644
--- a/lib/tdb/common/io.c
+++ b/lib/tdb/common/io.c
@@ -31,19 +31,29 @@
 /* check for an out of bounds access - if it is out of bounds then
    see if the database has been expanded by someone else and expand
    if necessary 
-   note that "len" is the minimum length needed for the db
 */
-static int tdb_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
+static int tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len,
+		   int probe)
 {
 	struct stat st;
-	if (len <= tdb->map_size)
+	if (len + off < len) {
+		if (!probe) {
+			/* Ensure ecode is set for log fn. */
+			tdb->ecode = TDB_ERR_IO;
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob off %d len %d wrap\n",
+				 (int)off, (int)len));
+		}
+		return -1;
+	}
+
+	if (off + len <= tdb->map_size)
 		return 0;
 	if (tdb->flags & TDB_INTERNAL) {
 		if (!probe) {
 			/* Ensure ecode is set for log fn. */
 			tdb->ecode = TDB_ERR_IO;
-			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %d beyond internal malloc size %d\n",
-				 (int)len, (int)tdb->map_size));
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond internal malloc size %u\n",
+				 (int)(off + len), (int)tdb->map_size));
 		}
 		return -1;
 	}
@@ -53,16 +63,25 @@ static int tdb_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
 		return -1;
 	}
 
-	if (st.st_size < (size_t)len) {
+	if (st.st_size < (size_t)off + len) {
 		if (!probe) {
 			/* Ensure ecode is set for log fn. */
 			tdb->ecode = TDB_ERR_IO;
-			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %d beyond eof at %d\n",
-				 (int)len, (int)st.st_size));
+			TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond eof at %u\n",
+				 (int)(off + len), (int)st.st_size));
 		}
 		return -1;
 	}
 
+	/* Beware >4G files! */
+	if ((tdb_off_t)st.st_size != st.st_size) {
+		/* Ensure ecode is set for log fn. */
+		tdb->ecode = TDB_ERR_IO;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_oob len %llu too large!\n",
+			 (long long)st.st_size));
+		return -1;
+	}
+
 	/* Unmap, update size, remap */
 	if (tdb_munmap(tdb) == -1) {
 		tdb->ecode = TDB_ERR_IO;
@@ -86,7 +105,7 @@ static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
 		return -1;
 	}
 
-	if (tdb->methods->tdb_oob(tdb, off + len, 0) != 0)
+	if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0)
 		return -1;
 
 	if (tdb->map_ptr) {
@@ -134,7 +153,7 @@ void *tdb_convert(void *buf, uint32_t size)
 static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf, 
 		    tdb_len_t len, int cv)
 {
-	if (tdb->methods->tdb_oob(tdb, off + len, 0) != 0) {
+	if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0) {
 		return -1;
 	}
 
@@ -307,7 +326,7 @@ int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
 	}
 
 	/* must know about any previous expansions by another process */
-	tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
+	tdb->methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 
 	/* limit size in order to avoid using up huge amounts of memory for
 	 * in memory tdbs if an oddball huge record creeps in */
@@ -434,7 +453,7 @@ int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
 		 * Optimize by avoiding the malloc/memcpy/free, point the
 		 * parser directly at the mmap area.
 		 */
-		if (tdb->methods->tdb_oob(tdb, offset+len, 0) != 0) {
+		if (tdb->methods->tdb_oob(tdb, offset, len, 0) != 0) {
 			return -1;
 		}
 		data.dptr = offset + (unsigned char *)tdb->map_ptr;
@@ -461,7 +480,7 @@ int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *r
 		TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%d\n", rec->magic, offset));
 		return -1;
 	}
-	return tdb->methods->tdb_oob(tdb, rec->next+sizeof(*rec), 0);
+	return tdb->methods->tdb_oob(tdb, rec->next, sizeof(*rec), 0);
 }
 
 int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c
index ec45689ffc..2965ea77b5 100644
--- a/lib/tdb/common/open.c
+++ b/lib/tdb/common/open.c
@@ -385,7 +385,17 @@ _PUBLIC_ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int td
 		goto fail;
 	}
 
+	/* Beware truncation! */
 	tdb->map_size = st.st_size;
+	if (tdb->map_size != st.st_size) {
+		/* Ensure ecode is set for log fn. */
+		tdb->ecode = TDB_ERR_IO;
+		TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
+			 "len %llu too large!\n", (long long)st.st_size));
+		errno = EIO;
+		goto fail;
+	}
+
 	tdb->device = st.st_dev;
 	tdb->inode = st.st_ino;
 	tdb_mmap(tdb);
diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h
index 140d4ecec5..3c6aabffc7 100644
--- a/lib/tdb/common/tdb_private.h
+++ b/lib/tdb/common/tdb_private.h
@@ -180,7 +180,7 @@ struct tdb_methods {
 	int (*tdb_read)(struct tdb_context *, tdb_off_t , void *, tdb_len_t , int );
 	int (*tdb_write)(struct tdb_context *, tdb_off_t, const void *, tdb_len_t);
 	void (*next_hash_chain)(struct tdb_context *, uint32_t *);
-	int (*tdb_oob)(struct tdb_context *, tdb_off_t , int );
+	int (*tdb_oob)(struct tdb_context *, tdb_off_t , tdb_len_t, int );
 	int (*tdb_expand_file)(struct tdb_context *, tdb_off_t , tdb_off_t );
 };
 
diff --git a/lib/tdb/common/transaction.c b/lib/tdb/common/transaction.c
index e4573cb0a9..66ecbfdefb 100644
--- a/lib/tdb/common/transaction.c
+++ b/lib/tdb/common/transaction.c
@@ -382,9 +382,10 @@ static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain
 /*
   out of bounds check during a transaction
 */
-static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
+static int transaction_oob(struct tdb_context *tdb, tdb_off_t off,
+			   tdb_len_t len, int probe)
 {
-	if (len <= tdb->map_size) {
+	if (off + len >= off && off + len <= tdb->map_size) {
 		return 0;
 	}
 	tdb->ecode = TDB_ERR_IO;
@@ -507,7 +508,7 @@ static int _tdb_transaction_start(struct tdb_context *tdb,
 
 	/* make sure we know about any file expansions already done by
 	   anyone else */
-	tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
+	tdb->methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 	tdb->transaction->old_map_size = tdb->map_size;
 
 	/* finally hook the io methods, replacing them with
@@ -741,7 +742,7 @@ static int tdb_recovery_allocate(struct tdb_context *tdb,
 	}
 
 	/* remap the file (if using mmap) */
-	methods->tdb_oob(tdb, tdb->map_size + 1, 1);
+	methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 
 	/* we have to reset the old map size so that we don't try to expand the file
 	   again in the transaction commit, which would destroy the recovery area */
@@ -980,7 +981,7 @@ static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 			return -1;
 		}
 		tdb->map_size = tdb->transaction->old_map_size;
-		methods->tdb_oob(tdb, tdb->map_size + 1, 1);
+		methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 	}
 
 	/* Keep the open lock until the actual commit */