On 10/23/2014 11:28 AM, Yury Gribov wrote: > On 10/23/2014 11:13 AM, Jakub Jelinek wrote: >> On Thu, Oct 23, 2014 at 11:11:29AM +0400, Yury Gribov wrote: >>> Hi all, >>> >>> On 09/29/2014 09:21 PM, Yury Gribov wrote: >>>>>> This patch enables -fsanitize-recover for KASan by default. This causes >>>>>> KASan to continue execution after error in case of inline >>>>>> instrumentation. This feature is needed because >>>>>> - reports during early bootstrap won't even be printed >>>>>> - needed to run all tests w/o rebooting machine for every test >>>>>> - needed for interactive work on desktop >>>> >>>> This is the third version of patch which renames -fsanitize-recover to >>>> -fubsan-recover and introduces -fasan-recover (enabled by default for >>>> KASan). It also moves flag handling to finish_options per Jakub's request. >>> >>> A new version of patch based upon Jakub's recent changes to >>> -fsanitize-recover=. I've renamed __asan_report_recover_load* to >>> __asan_report_load*_noabort to match UBSan's style. >>> >>> Note that currently -fsanitize=kernel-address >>> -fno-sanitize-recover=kernel-address won't work as expected because we miss >>> __asan_load*_abort family of functions in libasan. >> >> I thought __asan_* functions are provided by the kernel, not libasan, for >> -fsanitize=kernel-address. Or is kernel linked with real libasan.a or >> some stripped down version thereof? > > Hm, right, libasan is not linked to kernel so it indeed does not need any > changes. But now I see that for -fsanitize=kernel-address we need both > __asan_load* and __asan_load*_noabort (the latter > being default) depending on -fsanitize-recover setting. Let me update the > patch for this. >
IMO we don't need different versions of __asan_load* and __asan_load*_noabort, because -fno-sanitize-recover=kernel-address will never work with the linux kernel. I already said this before, and repeat this once again: There is few places in kernel where we validly touch poisoned memory, so we need to disable error reporting in runtime for such memory accesses. I use per-thread flag which is raised before the valid access to poisoned memory. This flag checked in __asan_report*() function. If it raised then we shouldn't print any error message, just silently exit from report. -fno-sanitize-recover=kernel-address will just cause early kernel crash on boot, so we will never use it.
