kernel compilation with stack protector

avian · 08-26-2014, 08:04 AM

Currently running 14.1, and have a question that may be bizzare, but would love an answer.

The default kernel that is installed in 14.1 seems to support the __stack_chk_fail symbol (according to /proc/kallsyms). When I try to compile my own kernel, the Makefile seems to add the -fno-stack-protector option to CFLAGS (after doing a "ifndef CONFIG_CC_STACKPROTECTOR_"). So obviously my resultant kernel does include support for the __stack_chk_fail symbol.

To cut a long story short, if I try to override the makefile by changing -fno-stack-protector to -fstack-protector, the compilation doesnt complete, with errors along the lines of "init/build-in.o: In function `name_to_dev_t': undefined reference to `__stack_chk_fail'", and so forth.

So my question is. Is it possible to copmile a kernel on 14.1 with support for the __stack_chk_fail symbol, and if so, how would one go about it?

tuxbg · 08-26-2014, 12:20 PM

This is mine

Code:

cat /proc/kallsyms | grep stack_chk
ffffffff81077240 T __stack_chk_fail

uname -r
3.15.7-1

55020 · 08-26-2014, 12:41 PM

Don't ever fiddle with the kernel makefiles when there is an option to do what you want to do.

Go into 'make menuconfig'
Go to "Processor type and features"
Go down to "Enable -fstack-protector buffer overflow detection" (towards the bottom, immediately above the timer frequency)
Enable it, save, and build.

Drakeo · 08-26-2014, 12:56 PM

welcome avian hope you find many answers you may need here.

avian · 08-26-2014, 07:58 PM

Quote:

Originally Posted by 55020

Don't ever fiddle with the kernel makefiles when there is an option to do what you want to do.

Go into 'make menuconfig'
Go to "Processor type and features"
Go down to "Enable -fstack-protector buffer overflow detection" (towards the bottom, immediately above the timer frequency)
Enable it, save, and build.

Thank you so much. You wont believe how many times I went through the config and missed that option.