Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 15 Feb 2017 11:34:26 +0100 | Subject | Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() |
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On Wed, Feb 15, 2017 at 10:18 AM, Dmitry Vyukov <dvyukov@google.com> wrote: > On Wed, Feb 15, 2017 at 12:03 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> Hi Arnd, > > Frankly it looks like something that needs to be fixed in compilers. > However, that probably won't happen in near future. > Our bet is on clang where we would be interested in fixing such issues. > > Alexander, can you please check how clang compares with gcc with asan > stack instrumentation on typecheck and READ_ONCE? > If clang introduces additional redzones due to code in typecheck and > READ_ONCE, then it looks like something that we need to fix. Not sure > why typecheck affects codegen at all... > > Re committing this change: Arnd, do you have an estimation on number > of changes we will need to land to enable the warning? If it's > handful, then it may be worth pursuing (but we still need a proper > impl for READ_ONCE).
My current estimate is only a handful of patches to enable CONFIG_FRAME_WARN=3072 with a clean build, and maybe a few dozen more to get down to 2048 with gcc-7.0.1 (no idea for older versions).
What I'm looking at now is this set of remaining warnings (>3072 bytes) and 24 other files >2048:
drivers/gpu/drm/i915/gvt/handlers.c:2200:1: error: the frame size of 30448 bytes is larger than 3000 bytes drivers/media/usb/em28xx/em28xx-dvb.c:2061:1: error: the frame size of 4264 bytes is larger than 3000 bytes drivers/staging/unisys/visorbus/visorchipset.c:1466:1: error: the frame size of 3008 bytes is larger than 3000 bytes fs/ocfs2/super.c:1219:1: error: the frame size of 3232 bytes is larger than 3000 bytes lib/lz4/lz4_compress.c:883:1: error: the frame size of 6696 bytes is larger than 3000 bytes lib/lz4/lz4hc_compress.c:579:1: error: the frame size of 5576 bytes is larger than 3000 bytes
and this set of patches I have applied locally, most of which need some more work:
# shown here earlier, need work rewrite READ_ONCE/WRITE_ONCE typecheck.h: avoid local variables in typecheck() macro # needs rewrite to use __uninline_for_kasan [SUBMITTED 20170208] netlink: move nla_put_{u8,u16,u32} out of line # pending for 4.11 or 4.12 [SUBMITTED 20170208] [media] tc358743: fix register i2c_rd/wr functions [SUBMITTED 20170214] rt2500usb: don't mark register accesses as inline # these just add more __uninline_for_kasan in driver specific code staging: dgnc: reduce stack usage with KASAN [media] i2c: cx25840: avoid stack overflow with KASAN [media] tuners: reduce stack usage with kasan [media] i2c: ks0127: reduce stack frame size [media] dvb-frontends: reduce stack size in i2c access [media] r820t: rewrite register access to reduce stack size tty: kbd: reduce stack size with KASAN
Arnd
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