Do proper bounds checking in formats (bug #1356)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@2694 65c4cc65-6c06-0410-ace0-fbb531ad65f3

formats/format_g729.c

@@ -183,8 +183,9 @@ static int g729_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = max - bytes;
 	if (whence != SEEK_FORCECUR) {
 		offset = (offset > max)?max:offset;
-		offset = (offset < min)?min:offset;
 	}
+	// protect against seeking beyond begining.
+	offset = (offset < min)?min:offset;
 	if (lseek(fs->fd, offset, SEEK_SET) < 0)
 		return -1;
 	return 0;

formats/format_gsm.c

@@ -197,9 +197,10 @@ static int gsm_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = distance + cur;
 	else if(whence == SEEK_END)
 		offset = max - distance;
+	// Always protect against seeking past the begining.
+	offset = (offset < min)?min:offset;
 	if (whence != SEEK_FORCECUR) {
 		offset = (offset > max)?max:offset;
-		offset = (offset < min)?min:offset;
 	} else if (offset > max) {
 		int i;
 		lseek(fs->fd, 0, SEEK_END);

formats/format_pcm.c

@@ -172,8 +172,9 @@ static int pcm_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = max - sample_offset;
 	if (whence != SEEK_FORCECUR) {
 		offset = (offset > max)?max:offset;
-		offset = (offset < min)?min:offset;
 	}
+	// always protect against seeking past begining.
+	offset = (offset < min)?min:offset;
 	return lseek(fs->fd, offset, SEEK_SET);
 }
 

formats/format_pcm_alaw.c

@@ -253,8 +253,9 @@ static int pcm_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = max - sample_offset;
 	if (whence != SEEK_FORCECUR) {
 		offset = (offset > max)?max:offset;
-		offset = (offset < min)?min:offset;
 	}
+	// Always protect against seeking past begining
+	offset = (offset < min)?min:offset;
 	return lseek(fs->fd, offset, SEEK_SET);
 }
 

formats/format_wav.c

@@ -525,8 +525,9 @@ static int wav_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = max - samples;
         if (whence != SEEK_FORCECUR) {
 		offset = (offset > max)?max:offset;
-		offset = (offset < min)?min:offset;
 	}
+	// always protect the header space.
+	offset = (offset < min)?min:offset;
 	return lseek(fs->fd,offset,SEEK_SET);
 }
 

formats/format_wav_gsm.c

@@ -493,8 +493,9 @@ static int wav_seek(struct ast_filestream *fs, long sample_offset, int whence)
 		offset = distance + cur;
 	else if(whence == SEEK_END)
 		offset = max - distance;
+	// always protect against seeking past end of header
+	offset = (offset < min)?min:offset;
 	if (whence != SEEK_FORCECUR) {
-		offset = (offset < min)?min:offset;
 		offset = (offset > max)?max:offset;
 	} else if (offset > max) {
 		int i;