When the fortify feature was first introduced in commit 6974f0c4555e
("include/linux/string.h: add the option of fortified string.h functions"),
Daniel Micay observed:
* It should be possible to optionally use __builtin_object_size(x, 1) for
some functions (C strings) to detect intra-object overflows (like
glibc's _FORTIFY_SOURCE=2), but for now this takes the conservative
approach to avoid likely compatibility issues.
This patch set:
- converts a number of string functions to use __builtin_object_size(x, 1)
- adds LKDTM tests for both types of fortified function.
This change passes an allyesconfig on powerpc and x86, and an x86 kernel
built with it survives running with syz-stress from syzkaller, so it seems
safe so far.
Daniel Axtens (2):
string.h: detect intra-object overflow in fortified string functions
lkdtm: tests for FORTIFY_SOURCE
drivers/misc/lkdtm/bugs.c | 51 ++++++++++++++++++++++++++++++++++++++
drivers/misc/lkdtm/core.c | 2 ++
drivers/misc/lkdtm/lkdtm.h | 2 ++
include/linux/string.h | 27 ++++++++++++--------
4 files changed, 71 insertions(+), 11 deletions(-)
--
2.20.1
