Red Hat Bugzilla – Bug 511187
kernel: build with -fno-delete-null-pointer-checks [mrg-1]
Last modified: 2016-05-22 19:28:26 EDT
+++ This bug was initially created as a clone of Bug #511181 +++
Description of problem:
Use global dataflow analysis to identify and eliminate useless checks for null pointers. The compiler assumes that dereferencing a null pointer would have halted the program. If a pointer is checked after it has already been dereferenced, it cannot be null.
In some environments, this assumption is not true, and programs can safely dereference null pointers. Use -fno-delete-null-pointer-checks to disable this optimization for programs which depend on that behavior.
Enabled at levels -O2, -O3, -Os.
Patch added to kernel -130
Verified by code review. Found upstream commit a3ca86aea507904148870946d599e07a340b39bf as mrg-rt.git commit ee25b4c4be4adad44a837c16ef7680d0b970b353 implemented as add_-fno-delete-null-pointer-checks_to_CFLAGS.patch in the kernel-rt-18.104.22.168-132 source RPM.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.