On Tue, Feb 12, 2019 at 7:08 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > This adjusts structleak to also work with non-struct types when they > are passed by reference, since those variables may leak just like > anything else. This is exposed via an improved set of Kconfig options. > (This does mean structleak is slightly misnamed now.) > > Building with CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL should give the > kernel complete initialization coverage of all stack variables passed > by reference, including padding (see lib/test_stackinit.c). > > Using CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE to count added initializations > under defconfig: > > ..._BYREF: 5945 added initializations > ..._BYREF_ALL: 16606 added initializations > > There is virtually no change to text+data size (both have less than 0.05% > growth): I just resumed my randconfig build testing after a longer break, and found a regression for stack usage that I bisected to your change. It shows up in a variety of files depending on the configuration, so far the worst one is the configuration at https://pastebin.com/UK54qbKa that leads to ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_start_search': ../drivers/media/dvb-frontends/stv090x.c:1595:1: error: the frame size of 5320 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_optimize_track': ../drivers/media/dvb-frontends/stv090x.c:3090:1: error: the frame size of 5872 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_algo': ../drivers/media/dvb-frontends/stv090x.c:3431:1: error: the frame size of 5144 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] } At least for this specific file, I also see a significant (though not alarming) increase in code size: text data bss dec hex filename 179196 4632 256 184084 2cf14 obj-x86/drivers/media/dvb-frontends/stv090x-before.o 216740 4632 256 221628 361bc obj-x86/drivers/media/dvb-frontends/stv090x-after.o Part of the problem here is definitely interaction with the asan-stack sanitizer. Changing asan-stack=1 to asan-stack=0, it looks a lot better: ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_start_search': ../drivers/media/dvb-frontends/stv090x.c:1595:1: warning: the frame size of 120 bytes is larger than 20 bytes [-Wframe-larger-than=] ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_optimize_track': ../drivers/media/dvb-frontends/stv090x.c:3090:1: warning: the frame size of 168 bytes is larger than 20 bytes [-Wframe-larger-than=] ../drivers/media/dvb-frontends/stv090x.c: In function 'stv090x_algo': ../drivers/media/dvb-frontends/stv090x.c:3431:1: warning: the frame size of 192 bytes is larger than 20 bytes [-Wframe-larger-than=] text data bss dec hex filename 184061 4632 256 188949 2e215 obj-x86/drivers/media/dvb-frontends/stv090x.o I get similar results with asan-stack=1 but without your plugin, only the combination of the two has the explosive stack size growth. I can help analyze this further, but maybe you can have a look first, there might be something obvious when you read the input to the plugin. Arnd
