__write_overflow declared with attribute error

Question

I'm using memset and memcpy in my linux kernel project. When I've tried to make the project, I got the following error:

In function ‘memset’, inlined from ‘init_minifw_read_write_module’ at /home/ido/CLionProjects/Firewall/KernelSpace/minfirewall.c:118:13: ./include/linux/string.h:327:3: error: call to ‘__write_overflow’ declared with attribute error: detected write beyond size of object passed as 1st parameter __write_overflow();

I didn't find any workaround for the above error.

Makefile:

obj-m += minfirewall.o
all:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

I'm running kernel version 4.18.0-15-generic.

Any ideas how to fix this error?

Andrejs Cainikovs · Accepted Answer · 2019-03-12 12:08:27Z

1

This is due to _FORTIFY_SOURCE feature for compile-time and run-time protection for finding overflows in the common string (e.g. strcpy, strcmp) and memory (e.g. memcpy, memcmp) functions. Info is here and here.

You can explicitly turn this feature off by passing -D_FORTIFY_SOURCE=0 (-U_FORTIFY_SOURCE will work as well) to the compiler.

EDIT:

It looks like you are building a Linux kernel module. Passing a compiler option for kernel module Makefile is a bit specific.

Add following to your Makefile:

CFLAGS_minfirewall.o := -D_FORTIFY_SOURCE=0

edited Mar 12, 2019 at 12:08

answered Mar 12, 2019 at 11:01

Andrejs Cainikovs

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8 Comments

Ido Segal Over a year ago

Can I passing it to the make file ?

Andrejs Cainikovs Over a year ago

Of course. It depends on how Makefile is written. Typically CFLAGS is already present in Makefile, so you just need to add -D_FORTIFY_SOURCE=0 to CFLAGS variable. Show me your Makefile, and I can tell you how to do this exactly.

Andrejs Cainikovs Over a year ago

If Makefile is well written, it might give you possibility to pass CFLAGS via command line: make CFLAGS=-D_FORTIFY_SOURCE=0.

Ido Segal Over a year ago

I passed make CFLAGS=-D_FORTIFY_SOURCE=0 and got "gcc: error: _FORTIFY_SOURCE=0: No such file or directory"

Andrejs Cainikovs Over a year ago

Then, as I said, try to add -D_FORTIFY_SOURCE=0 to CFLAGS within Makefile.

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