[PATCH] D91405: [clangd] Assert on varint encoding

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet created this revision.
kadircet added a reviewer: sammccall.
Herald added subscribers: cfe-commits, usaxena95, arphaman.
Herald added a project: clang.
kadircet requested review of this revision.
Herald added subscribers: MaskRay, ilya-biryukov.

5th byte of a varint can't be bigger than 0x0f, fix a test and add an
assertion.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91405

Files:
  clang-tools-extra/clangd/index/Serialization.cpp
  clang-tools-extra/clangd/unittests/SerializationTests.cpp


Index: clang-tools-extra/clangd/unittests/SerializationTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/SerializationTests.cpp
+++ clang-tools-extra/clangd/unittests/SerializationTests.cpp
@@ -366,9 +366,9 @@
   Pos += FileDigest.size();
 
   // Varints are little-endian base-128 numbers, where the top-bit of each byte
-  // indicates whether there are more. 8fffffff7f -> 0xffffffff.
+  // indicates whether there are more. 8fffffff0f -> 0xffffffff.
   std::string CorruptSrcs =
-      (Srcs->Data.take_front(Pos) + llvm::fromHex("8fffffff7f") +
+      (Srcs->Data.take_front(Pos) + llvm::fromHex("8fffffff0f") +
        "some_random_garbage")
           .str();
   Srcs->Data = CorruptSrcs;
Index: clang-tools-extra/clangd/index/Serialization.cpp
===================================================================
--- clang-tools-extra/clangd/index/Serialization.cpp
+++ clang-tools-extra/clangd/index/Serialization.cpp
@@ -87,6 +87,7 @@
     uint32_t Val = B & ~More;
     for (int Shift = 7; B & More && Shift < 32; Shift += 7) {
       B = consume8();
+      assert((B & ~More) < (1 << (32 - Shift)) && "Invalid varint encoding");
       Val |= (B & ~More) << Shift;
     }
     return Val;



Index: clang-tools-extra/clangd/unittests/SerializationTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/SerializationTests.cpp
+++ clang-tools-extra/clangd/unittests/SerializationTests.cpp
@@ -366,9 +366,9 @@
   Pos += FileDigest.size();
 
   // Varints are little-endian base-128 numbers, where the top-bit of each byte
-  // indicates whether there are more. 8fffffff7f -> 0xffffffff.
+  // indicates whether there are more. 8fffffff0f -> 0xffffffff.
   std::string CorruptSrcs =
-      (Srcs->Data.take_front(Pos) + llvm::fromHex("8fffffff7f") +
+      (Srcs->Data.take_front(Pos) + llvm::fromHex("8fffffff0f") +
        "some_random_garbage")
           .str();
   Srcs->Data = CorruptSrcs;
Index: clang-tools-extra/clangd/index/Serialization.cpp
===================================================================
--- clang-tools-extra/clangd/index/Serialization.cpp
+++ clang-tools-extra/clangd/index/Serialization.cpp
@@ -87,6 +87,7 @@
     uint32_t Val = B & ~More;
     for (int Shift = 7; B & More && Shift < 32; Shift += 7) {
       B = consume8();
+      assert((B & ~More) < (1 << (32 - Shift)) && "Invalid varint encoding");
       Val |= (B & ~More) << Shift;
     }
     return Val;

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