From f5736f87f286dfe13760b7789c6fee3f35be5a57 Mon Sep 17 00:00:00 2001 From: Argyrios Kyrtzidis Date: Thu, 5 Apr 2012 04:23:56 +0000 Subject: [PATCH] In MemoryBuffer::getOpenFile() make sure that the buffer is null-terminated if the caller requested a null-terminated one. When mapping the file there could be a racing issue that resulted in the file being larger than the FileSize passed by the caller. We already have an assertion for this in MemoryBuffer::init() but have a runtime guarantee that the buffer will be null-terminated, so do a copy that adds a null-terminator. Protects against crash of rdar://11161822. llvm-svn: 154082 --- lib/Support/MemoryBuffer.cpp | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/lib/Support/MemoryBuffer.cpp b/lib/Support/MemoryBuffer.cpp index 911a03f8088..16e5c7a9f72 100644 --- a/lib/Support/MemoryBuffer.cpp +++ b/lib/Support/MemoryBuffer.cpp @@ -304,6 +304,16 @@ error_code MemoryBuffer::getOpenFile(int FD, const char *Filename, RealMapOffset)) { result.reset(GetNamedBuffer( StringRef(Pages + Delta, MapSize), Filename, RequiresNullTerminator)); + + if (RequiresNullTerminator && result->getBufferEnd()[0] != '\0') { + // There could be a racing issue that resulted in the file being larger + // than the FileSize passed by the caller. We already have an assertion + // for this in MemoryBuffer::init() but have a runtime guarantee that + // the buffer will be null-terminated here, so do a copy that adds a + // null-terminator. + result.reset(MemoryBuffer::getMemBufferCopy(result->getBuffer(), + Filename)); + } return error_code::success(); } } @@ -339,6 +349,7 @@ error_code MemoryBuffer::getOpenFile(int FD, const char *Filename, if (NumRead == 0) { assert(0 && "We got inaccurate FileSize value or fstat reported an " "invalid file size."); + *BufPtr = '\0'; // null-terminate at the actual size. break; } BytesLeft -= NumRead;