Improve the reporting of buffer overflows under CONFIG_FORTIFY_SOURCE to
help accelerate debugging efforts. The calculations are all just sitting
in registers anyway, so pass them along to the function to be reported.
For example, before:
detected buffer overflow in memcpy
and after:
memcpy: detected buffer overflow: 4096 byte read of buffer size 1
Link: https://lore.kernel.org/r/20230407192717.636137-10-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
In preparation for KUnit testing and further improvements in fortify
failure reporting, split out the report and encode the function and access
failure (read or write overflow) into a single u8 argument. This mainly
ends up saving a tiny bit of space in the data segment. For a defconfig
with FORTIFY_SOURCE enabled:
$ size gcc/vmlinux.before gcc/vmlinux.after
text data bss dec hex filename
26132309 9760658 2195460 38088427 2452eeb gcc/vmlinux.before
26132386 9748382 2195460 38076228 244ff44 gcc/vmlinux.after
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
A number of prototypes are missing for the decompressor, some
of them are in the .c files that contain the callers, but are
invisible at the function definition:
arch/arm/boot/compressed/misc.c:129:17: error: no previous prototype for '__div0' [-Werror=missing-prototypes]
arch/arm/boot/compressed/misc.c:138:1: error: no previous prototype for 'decompress_kernel' [-Werror=missing-prototypes]
arch/arm/boot/compressed/misc.c:163:6: error: no previous prototype for 'fortify_panic' [-Werror=missing-prototypes]
arch/arm/boot/compressed/decompress.c:63:5: error: no previous prototype for 'do_decompress' [-Werror=missing-prototypes]
arch/arm/boot/compressed/fdt_check_mem_start.c:63:10: error: no previous prototype for 'fdt_check_mem_start' [-Werror=missing-prototypes]
Move these all to misc.h so they are visible by the callee as well.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Commit ee333554fe ("ARM: 8749/1: Kconfig: Add ARCH_HAS_FORTIFY_SOURCE")
introduced a new warning:
arch/arm/boot/compressed/misc.c: In function 'fortify_panic':
arch/arm/boot/compressed/misc.c:167:1: error: 'noreturn' function does return [-Werror]
The simple solution would be to make 'error' a noreturn function, but
this causes a prototype mismatch as the function is prototyped in
several .c files. So, move the function prototype to a new header.
There are also a couple of variables that are also declared in several
locations. Clean this up while we are here.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Kees Cook