From: Francis Laniel <laniel_francis@xxxxxxxxxxxxxxxxxxx> Hi. I hope your families, friends and yourselves are fine. This patch set answers to this issue: https://github.com/KSPP/linux/issues/46 I based my modifications on top of two patches from Daniel Axtens which modify calls to __builtin_object_size to ensure the true size of char * are returned and not the surrounding structure size. To sum up, in my first patch I implemented a fortified version of strscpy. This new version ensures the following before calling vanilla strscpy: 1. There is no read overflow because either size is smaller than src length or we shrink size to src length by calling fortified strnlen. 2. There is no write overflow because we either failed during compilation or at runtime by checking that size is smaller than dest size. The second patch brings a new file in LKDTM driver to test this new version. The test ensures the fortified version still returns the same value as the vanilla one while panic'ing when there is a write overflow. The third just corrects some typos in LKDTM related file. If you see any problem or way to improve the code, feel free to share it. Best regards. Daniel Axtens (2): string.h: detect intra-object overflow in fortified string functions lkdtm: tests for FORTIFY_SOURCE Francis Laniel (3): string.h: Add FORTIFY coverage for strscpy() Add new file in LKDTM to test fortified strscpy. Correct wrong filenames in comment. drivers/misc/lkdtm/Makefile | 1 + drivers/misc/lkdtm/bugs.c | 50 +++++++++++++++ drivers/misc/lkdtm/core.c | 3 + drivers/misc/lkdtm/fortify.c | 82 +++++++++++++++++++++++++ drivers/misc/lkdtm/lkdtm.h | 19 +++--- include/linux/string.h | 75 ++++++++++++++++++---- tools/testing/selftests/lkdtm/tests.txt | 1 + 7 files changed, 213 insertions(+), 18 deletions(-) create mode 100644 drivers/misc/lkdtm/fortify.c -- 2.20.1
