4 files changed, 38 insertions, 8 deletions

diff --git a/api/file.go b/api/file.go
index 94eea516a..f65be145d 100644
--- a/api/file.go
+++ b/api/file.go
@@ -52,6 +52,8 @@ const (
 	RotatedCCW         = 6
 	RotatedCCWMirrored = 7
 	RotatedCW          = 8
+
+	MaxImageSize = 4096 * 2160 // 4k resolution
 )
 
 var fileInfoCache *utils.Cache = utils.NewLru(1000)
@@ -125,6 +127,21 @@ func uploadFile(c *Context, w http.ResponseWriter, r *http.Request) {
 
 		uid := model.NewId()
 
+		if model.IsFileExtImage(filepath.Ext(files[i].Filename)) {
+			imageNameList = append(imageNameList, uid+"/"+filename)
+			imageDataList = append(imageDataList, buf.Bytes())
+
+			// Decode image config first to check dimensions before loading the whole thing into memory later on
+			config, _, err := image.DecodeConfig(bytes.NewReader(buf.Bytes()))
+			if err != nil {
+				c.Err = model.NewAppError("uploadFile", "Unable to upload image file.", err.Error())
+				return
+			} else if config.Width*config.Height > MaxImageSize {
+				c.Err = model.NewAppError("uploadFile", "Unable to upload image file. File is too large.", err.Error())
+				return
+			}
+		}
+
 		path := "teams/" + c.Session.TeamId + "/channels/" + channelId + "/users/" + c.Session.UserId + "/" + uid + "/" + filename
 
 		if err := writeFile(buf.Bytes(), path); err != nil {
@@ -132,11 +149,6 @@ func uploadFile(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		if model.IsFileExtImage(filepath.Ext(files[i].Filename)) {
-			imageNameList = append(imageNameList, uid+"/"+filename)
-			imageDataList = append(imageDataList, buf.Bytes())
-		}
-
 		encName := utils.UrlEncode(filename)
 
 		fileUrl := "/" + channelId + "/" + c.Session.UserId + "/" + uid + "/" + encName
diff --git a/api/user.go b/api/user.go
index 06e5336f1..3796a50ee 100644
--- a/api/user.go
+++ b/api/user.go
@@ -855,6 +855,18 @@ func uploadProfileImage(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Decode image config first to check dimensions before loading the whole thing into memory later on
+	config, _, err := image.DecodeConfig(file)
+	if err != nil {
+		c.Err = model.NewAppError("uploadProfileFile", "Could not decode profile image config.", err.Error())
+		return
+	} else if config.Width*config.Height > MaxImageSize {
+		c.Err = model.NewAppError("uploadProfileFile", "Unable to upload profile image. File is too large.", err.Error())
+		return
+	}
+
+	file.Seek(0, 0)
+
 	// Decode image into Image object
 	img, _, err := image.Decode(file)
 	if err != nil {
diff --git a/web/react/components/create_post.jsx b/web/react/components/create_post.jsx
index b74f1871c..32ee31efe 100644
--- a/web/react/components/create_post.jsx
+++ b/web/react/components/create_post.jsx
@@ -253,8 +253,14 @@ export default class CreatePost extends React.Component {
         this.setState({uploadsInProgress: draft.uploadsInProgress, previews: draft.previews});
     }
     handleUploadError(err, clientId) {
+        let message = err;
+        if (message && typeof message !== 'string') {
+            // err is an AppError from the server
+            message = err.message;
+        }
+
         if (clientId === -1) {
-            this.setState({serverError: err});
+            this.setState({serverError: message});
         } else {
             const draft = PostStore.getDraft(this.state.channelId);
 
@@ -265,7 +271,7 @@ export default class CreatePost extends React.Component {
 
             PostStore.storeDraft(this.state.channelId, draft);
 
-            this.setState({uploadsInProgress: draft.uploadsInProgress, serverError: err});
+            this.setState({uploadsInProgress: draft.uploadsInProgress, serverError: message});
         }
     }
     handleTextDrop(text) {
diff --git a/web/react/components/user_settings/user_settings_general.jsx b/web/react/components/user_settings/user_settings_general.jsx
index 70e559c30..1c8ce3c79 100644
--- a/web/react/components/user_settings/user_settings_general.jsx
+++ b/web/react/components/user_settings/user_settings_general.jsx
@@ -171,7 +171,7 @@ export default class UserSettingsGeneralTab extends React.Component {
             }.bind(this),
             function imageUploadFailure(err) {
                 var state = this.setupInitialState(this.props);
-                state.serverError = err;
+                state.serverError = err.message;
                 this.setState(state);
             }.bind(this)
         );