From 2f8a08f31b1bfdc18766bae4983d238ee1cf716c Mon Sep 17 00:00:00 2001 From: Thiago Macieira Date: Wed, 14 Jun 2017 15:06:09 -0700 Subject: Make qt_check_pointer more OOM-safe First, it can never return, so we can mark it Q_NORETURN and add an std::termianate at the end. Though if it did, we'd end up in a null- pointer dereference crash in the caller. Second, add Q_DECL_NOTHROW to it. It can't throw, but it terminates execution. This also prevents both puts and fprintf from escaping via pthread asynchronous cancellation on Linux/glibc. Third, don't use QMessageLogger, since that allocates memory and actually uses QString. If we really are in an OOM situation, then QString's failed allocation would recurse back into qt_check_pointer. We'd compound the OOM situation with a stack overflow... Change-Id: Ia53158e207a94bf49489fffd14c81c47971f4e82 Reviewed-by: Friedemann Kleint Reviewed-by: Thiago Macieira --- src/corelib/global/qglobal.cpp | 17 ++++++++++++----- src/corelib/global/qglobal.h | 2 +- 2 files changed, 13 insertions(+), 6 deletions(-) (limited to 'src/corelib/global') diff --git a/src/corelib/global/qglobal.cpp b/src/corelib/global/qglobal.cpp index 4f0110dca4..9b76c72c0d 100644 --- a/src/corelib/global/qglobal.cpp +++ b/src/corelib/global/qglobal.cpp @@ -3016,13 +3016,20 @@ QString QSysInfo::machineHostName() If this macro is used outside a function, the behavior is undefined. */ -/* - The Q_CHECK_PTR macro calls this function if an allocation check - fails. +/*! + \internal + The Q_CHECK_PTR macro calls this function if an allocation check + fails. */ -void qt_check_pointer(const char *n, int l) +void qt_check_pointer(const char *n, int l) Q_DECL_NOTHROW { - QMessageLogger(n, l, nullptr).fatal("Out of memory"); + // make separate printing calls so that the first one may flush; + // the second one could want to allocate memory (fputs prints a + // newline and stderr auto-flushes). + fputs("Out of memory", stderr); + fprintf(stderr, " in %s, line %d\n", n, l); + + std::terminate(); } /* diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h index f2f28343c6..0c74ed4a3e 100644 --- a/src/corelib/global/qglobal.h +++ b/src/corelib/global/qglobal.h @@ -753,7 +753,7 @@ template <> class QStaticAssertFailure {}; #define Q_STATIC_ASSERT_X(Condition, Message) Q_STATIC_ASSERT(Condition) #endif -Q_CORE_EXPORT void qt_check_pointer(const char *, int); +Q_NORETURN Q_CORE_EXPORT void qt_check_pointer(const char *, int) Q_DECL_NOTHROW; Q_CORE_EXPORT void qBadAlloc(); #ifdef QT_NO_EXCEPTIONS -- cgit v1.2.3