commit 58a5fb56c33a
Author: Francois Marier <francois@mozilla.com>
Date:   Thu Feb 15 12:30:40 2018 -0800

    Bug 1435859 - Fix OOM crash on filenames without extensions. r=gcp, a=RyanVM
    
    Passing a value of -1 to nsCString::Truncate() converts that
    value to a large integer and leads to an unnecessary 4GB
    memory allocation.
    
    MozReview-Commit-ID: Icm5iUsEgA6
    
    --HG--
    extra : source : d418ce8a05644edb16f317c13fc1c8cd2b6c3c2f
---
 toolkit/components/url-classifier/Classifier.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git toolkit/components/url-classifier/Classifier.cpp toolkit/components/url-classifier/Classifier.cpp
index 9946469268fa..d5ba67fe300a 100644
--- toolkit/components/url-classifier/Classifier.cpp
+++ toolkit/components/url-classifier/Classifier.cpp
@@ -359,8 +359,13 @@ Classifier::DeleteTables(nsIFile* aDirectory, const nsTArray<nsCString>& aTables
     rv = file->GetNativeLeafName(leafName);
     NS_ENSURE_SUCCESS_VOID(rv);
 
-    leafName.Truncate(leafName.RFind("."));
-    if (aTables.Contains(leafName)) {
+    // Remove file extension if there's one.
+    int32_t dotPosition = leafName.RFind(".");
+    if (dotPosition >= 0) {
+      leafName.Truncate(dotPosition);
+    }
+
+    if (!leafName.IsEmpty() && aTables.Contains(leafName)) {
       if (NS_FAILED(file->Remove(false))) {
         NS_WARNING(nsPrintfCString("Fail to remove file %s from the disk",
                                    leafName.get()).get());