diff --git a/modules/git/commit.go b/modules/git/commit.go
index c86ece984..2f7f53e7c 100644
--- a/modules/git/commit.go
+++ b/modules/git/commit.go
@@ -169,6 +169,7 @@ func AddChanges(repoPath string, all bool, files ...string) error {
 	if all {
 		cmd.AddArguments("--all")
 	}
+	cmd.AddArguments("--")
 	_, err := cmd.AddArguments(files...).RunInDir(repoPath)
 	return err
 }
@@ -304,6 +305,7 @@ func (c *Commit) GetFilesChangedSinceCommit(pastCommit string) ([]string, error)
 }
 
 // FileChangedSinceCommit Returns true if the file given has changed since the the past commit
+// YOU MUST ENSURE THAT pastCommit is a valid commit ID.
 func (c *Commit) FileChangedSinceCommit(filename, pastCommit string) (bool, error) {
 	return c.repo.FileChangedBetweenCommits(filename, pastCommit, c.ID.String())
 }
diff --git a/modules/git/repo.go b/modules/git/repo.go
index 8a40fb1b9..28e54a1bb 100644
--- a/modules/git/repo.go
+++ b/modules/git/repo.go
@@ -187,8 +187,7 @@ func Pull(repoPath string, opts PullRemoteOptions) error {
 	if opts.All {
 		cmd.AddArguments("--all")
 	} else {
-		cmd.AddArguments(opts.Remote)
-		cmd.AddArguments(opts.Branch)
+		cmd.AddArguments("--", opts.Remote, opts.Branch)
 	}
 
 	if opts.Timeout <= 0 {
@@ -213,7 +212,7 @@ func Push(repoPath string, opts PushOptions) error {
 	if opts.Force {
 		cmd.AddArguments("-f")
 	}
-	cmd.AddArguments(opts.Remote, opts.Branch)
+	cmd.AddArguments("--", opts.Remote, opts.Branch)
 	_, err := cmd.RunInDirWithEnv(repoPath, opts.Env)
 	return err
 }
diff --git a/modules/git/repo_branch.go b/modules/git/repo_branch.go
index 05eba1e30..9209f4a76 100644
--- a/modules/git/repo_branch.go
+++ b/modules/git/repo_branch.go
@@ -135,7 +135,7 @@ func (repo *Repository) DeleteBranch(name string, opts DeleteBranchOptions) erro
 		cmd.AddArguments("-d")
 	}
 
-	cmd.AddArguments(name)
+	cmd.AddArguments("--", name)
 	_, err := cmd.RunInDir(repo.Path)
 
 	return err
diff --git a/modules/git/repo_commit.go b/modules/git/repo_commit.go
index 733991612..28374298c 100644
--- a/modules/git/repo_commit.go
+++ b/modules/git/repo_commit.go
@@ -117,20 +117,26 @@ func (repo *Repository) getCommit(id SHA1) (*Commit, error) {
 	return commit, nil
 }
 
-// GetCommit returns commit object of by ID string.
-func (repo *Repository) GetCommit(commitID string) (*Commit, error) {
+// ConvertToSHA1 returns a Hash object from a potential ID string
+func (repo *Repository) ConvertToSHA1(commitID string) (SHA1, error) {
 	if len(commitID) != 40 {
 		var err error
-		actualCommitID, err := NewCommand("rev-parse", commitID).RunInDir(repo.Path)
+		actualCommitID, err := NewCommand("rev-parse", "--verify", commitID).RunInDir(repo.Path)
 		if err != nil {
-			if strings.Contains(err.Error(), "unknown revision or path") {
-				return nil, ErrNotExist{commitID, ""}
+			if strings.Contains(err.Error(), "unknown revision or path") ||
+				strings.Contains(err.Error(), "fatal: Needed a single revision") {
+				return SHA1{}, ErrNotExist{commitID, ""}
 			}
-			return nil, err
+			return SHA1{}, err
 		}
 		commitID = actualCommitID
 	}
-	id, err := NewIDFromString(commitID)
+	return NewIDFromString(commitID)
+}
+
+// GetCommit returns commit object of by ID string.
+func (repo *Repository) GetCommit(commitID string) (*Commit, error) {
+	id, err := repo.ConvertToSHA1(commitID)
 	if err != nil {
 		return nil, err
 	}
@@ -243,6 +249,7 @@ func (repo *Repository) getFilesChanged(id1, id2 string) ([]string, error) {
 }
 
 // FileChangedBetweenCommits Returns true if the file changed between commit IDs id1 and id2
+// You must ensure that id1 and id2 are valid commit ids.
 func (repo *Repository) FileChangedBetweenCommits(filename, id1, id2 string) (bool, error) {
 	stdout, err := NewCommand("diff", "--name-only", "-z", id1, id2, "--", filename).RunInDirBytes(repo.Path)
 	if err != nil {
diff --git a/modules/git/repo_commit_test.go b/modules/git/repo_commit_test.go
index c0fdd1697..6d8ee6453 100644
--- a/modules/git/repo_commit_test.go
+++ b/modules/git/repo_commit_test.go
@@ -58,5 +58,5 @@ func TestGetCommitWithBadCommitID(t *testing.T) {
 	commit, err := bareRepo1.GetCommit("bad_branch")
 	assert.Nil(t, commit)
 	assert.Error(t, err)
-	assert.EqualError(t, err, "object does not exist [id: bad_branch, rel_path: ]")
+	assert.True(t, IsErrNotExist(err))
 }
diff --git a/modules/git/repo_compare.go b/modules/git/repo_compare.go
index ddc810972..7d66a2dc0 100644
--- a/modules/git/repo_compare.go
+++ b/modules/git/repo_compare.go
@@ -39,7 +39,7 @@ func (repo *Repository) GetMergeBase(tmpRemote string, base, head string) (strin
 		}
 	}
 
-	stdout, err := NewCommand("merge-base", base, head).RunInDir(repo.Path)
+	stdout, err := NewCommand("merge-base", "--", base, head).RunInDir(repo.Path)
 	return strings.TrimSpace(stdout), base, err
 }
 
diff --git a/modules/git/repo_index.go b/modules/git/repo_index.go
index 4d26563a9..2c351e209 100644
--- a/modules/git/repo_index.go
+++ b/modules/git/repo_index.go
@@ -12,7 +12,7 @@ import (
 // ReadTreeToIndex reads a treeish to the index
 func (repo *Repository) ReadTreeToIndex(treeish string) error {
 	if len(treeish) != 40 {
-		res, err := NewCommand("rev-parse", treeish).RunInDir(repo.Path)
+		res, err := NewCommand("rev-parse", "--verify", treeish).RunInDir(repo.Path)
 		if err != nil {
 			return err
 		}
diff --git a/modules/git/repo_tag.go b/modules/git/repo_tag.go
index 6d490af9b..20c36bd70 100644
--- a/modules/git/repo_tag.go
+++ b/modules/git/repo_tag.go
@@ -29,13 +29,13 @@ func (repo *Repository) IsTagExist(name string) bool {
 
 // CreateTag create one tag in the repository
 func (repo *Repository) CreateTag(name, revision string) error {
-	_, err := NewCommand("tag", name, revision).RunInDir(repo.Path)
+	_, err := NewCommand("tag", "--", name, revision).RunInDir(repo.Path)
 	return err
 }
 
 // CreateAnnotatedTag create one annotated tag in the repository
 func (repo *Repository) CreateAnnotatedTag(name, message, revision string) error {
-	_, err := NewCommand("tag", "-a", "-m", message, name, revision).RunInDir(repo.Path)
+	_, err := NewCommand("tag", "-a", "-m", message, "--", name, revision).RunInDir(repo.Path)
 	return err
 }
 
@@ -153,7 +153,7 @@ func (repo *Repository) GetTagNameBySHA(sha string) (string, error) {
 
 // GetTagID returns the object ID for a tag (annotated tags have both an object SHA AND a commit SHA)
 func (repo *Repository) GetTagID(name string) (string, error) {
-	stdout, err := NewCommand("show-ref", name).RunInDir(repo.Path)
+	stdout, err := NewCommand("show-ref", "--", name).RunInDir(repo.Path)
 	if err != nil {
 		return "", err
 	}
diff --git a/modules/git/repo_tree.go b/modules/git/repo_tree.go
index 4b9e61f26..b31e4330c 100644
--- a/modules/git/repo_tree.go
+++ b/modules/git/repo_tree.go
@@ -26,7 +26,7 @@ func (repo *Repository) getTree(id SHA1) (*Tree, error) {
 // GetTree find the tree object in the repository.
 func (repo *Repository) GetTree(idStr string) (*Tree, error) {
 	if len(idStr) != 40 {
-		res, err := NewCommand("rev-parse", idStr).RunInDir(repo.Path)
+		res, err := NewCommand("rev-parse", "--verify", idStr).RunInDir(repo.Path)
 		if err != nil {
 			return nil, err
 		}
diff --git a/modules/repofiles/delete.go b/modules/repofiles/delete.go
index 3d9b06b1c..a8ab277b2 100644
--- a/modules/repofiles/delete.go
+++ b/modules/repofiles/delete.go
@@ -92,6 +92,12 @@ func DeleteRepoFile(repo *models.Repository, doer *models.User, opts *DeleteRepo
 	// Assigned LastCommitID in opts if it hasn't been set
 	if opts.LastCommitID == "" {
 		opts.LastCommitID = commit.ID.String()
+	} else {
+		lastCommitID, err := t.gitRepo.ConvertToSHA1(opts.LastCommitID)
+		if err != nil {
+			return nil, fmt.Errorf("DeleteRepoFile: Invalid last commit ID: %v", err)
+		}
+		opts.LastCommitID = lastCommitID.String()
 	}
 
 	// Get the files in the index
diff --git a/modules/repofiles/update.go b/modules/repofiles/update.go
index 21df77606..26b5113f1 100644
--- a/modules/repofiles/update.go
+++ b/modules/repofiles/update.go
@@ -190,6 +190,13 @@ func CreateOrUpdateRepoFile(repo *models.Repository, doer *models.User, opts *Up
 	// Assigned LastCommitID in opts if it hasn't been set
 	if opts.LastCommitID == "" {
 		opts.LastCommitID = commit.ID.String()
+	} else {
+		lastCommitID, err := t.gitRepo.ConvertToSHA1(opts.LastCommitID)
+		if err != nil {
+			return nil, fmt.Errorf("DeleteRepoFile: Invalid last commit ID: %v", err)
+		}
+		opts.LastCommitID = lastCommitID.String()
+
 	}
 
 	encoding := "UTF-8"
diff --git a/modules/structs/repo_file.go b/modules/structs/repo_file.go
index b2eeb7f13..cb836e2e2 100644
--- a/modules/structs/repo_file.go
+++ b/modules/structs/repo_file.go
@@ -10,9 +10,9 @@ type FileOptions struct {
 	// message (optional) for the commit of this file. if not supplied, a default message will be used
 	Message string `json:"message"`
 	// branch (optional) to base this file from. if not given, the default branch is used
-	BranchName string `json:"branch"`
+	BranchName string `json:"branch" binding:"GitRefName;MaxSize(100)"`
 	// new_branch (optional) will make a new branch from `branch` before creating the file
-	NewBranchName string `json:"new_branch"`
+	NewBranchName string `json:"new_branch" binding:"GitRefName;MaxSize(100)"`
 	// `author` and `committer` are optional (if only one is given, it will be used for the other, otherwise the authenticated user will be used)
 	Author    Identity `json:"author"`
 	Committer Identity `json:"committer"`