linux/drivers/misc/lkdtm_rodata.c, branch v4.9

lkdtm: Mark lkdtm_rodata_do_nothing() notrace

2016-08-31T11:12:38Z

lkdtm_rodata_do_nothing() is an empty function which is generated in order to test the non-executability of rodata. Currently if function tracing is enabled then an mcount callsite will be generated for lkdtm_rodata_do_nothing(), and it will appear in the list of available functions for function tracing (available_filter_functions). Given it's purpose purely as a test function, it seems preferable for lkdtm_rodata_do_nothing() to be marked notrace, so it doesn't appear as traceable. This also avoids triggering a linker bug on powerpc: https://sourceware.org/bugzilla/show_bug.cgi?id=20428 When the linker sees code that needs to generate a call stub, eg. a branch to mcount(), it assumes the section is executable and dereferences a NULL pointer leading to a linker segfault. Marking lkdtm_rodata_do_nothing() notrace avoids triggering the bug because the function contains no other function calls. Signed-off-by: Michael Ellerman Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

lkdtm: silence warnings about function declarations

2016-07-15T23:14:45Z

When building under W=1, the lack of lkdtm.h in lkdtm_usercopy.c and lkdtm_rodata.c was discovered. This fixes the issue and consolidates the common header and the pr_fmt macro for simplicity and regularity across each test source file. Signed-off-by: Kees Cook

lkdtm: add function for testing .rodata section

2016-06-10T22:57:50Z

This adds a function that lives in the .rodata section. The section flags are corrected using objcopy since there is no way with gcc to declare section flags in an architecture-agnostic way. Signed-off-by: Kees Cook