Commits
Mark Rutland committed 824e71d68aa
BACKPORT: lib: harden strncpy_from_user The strncpy_from_user() accessor is effectively a copy_from_user() specialised to copy strings, terminating early at a NUL byte if possible. In other respects it is identical, and can be used to copy an arbitrarily large buffer from userspace into the kernel. Conceptually, it exposes a similar attack surface. As with copy_from_user(), we check the destination range when the kernel is built with KASAN, but unlike copy_from_user() we do not check the destination buffer when using HARDENED_USERCOPY. As strncpy_from_user() calls get_user() in a loop, we must call check_object_size() explicitly. This patch adds this instrumentation to strncpy_from_user(), per the same rationale as with the regular copy_from_user(). In the absence of hardened usercopy this will have no impact as the instrumentation expands to an empty static inline function. Link: http://lkml.kernel.org/r/1472221903-31181-1-git-send-email-mark.rutland@arm.com Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Bug: 31374226 Change-Id: I898e4e9f19307e37a9be497cb1a0d7f1e3911661 (cherry picked from commit bf90e56e467ed5766722972d483e6711889ed1b0) Signed-off-by: Sami Tolvanen <samitolvanen@google.com>