On Wed, 1 Feb 2023 21:25:51 -0800 Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > From: David Gow <davidgow@xxxxxxxxxx> > > commit be4f1ae978ffe98cc95ec49ceb95386fb4474974 upstream. > > KASAN errors will currently trigger a panic when panic_on_warn is set. > This renders kasan_multishot useless, as further KASAN errors won't be > reported if the kernel has already paniced. By making kasan_multishot > disable this behaviour for KASAN errors, we can still have the benefits of > panic_on_warn for non-KASAN warnings, yet be able to use kasan_multishot. > > This is particularly important when running KASAN tests, which need to > trigger multiple KASAN errors: previously these would panic the system if > panic_on_warn was set, now they can run (and will panic the system should > non-KASAN warnings show up). > > Signed-off-by: David Gow <davidgow@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx> > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> > Cc: Patricia Alfonso <trishalfonso@xxxxxxxxxx> > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > Cc: Shuah Khan <shuah@xxxxxxxxxx> > Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx> > Link: https://lkml.kernel.org/r/20200915035828.570483-6-davidgow@xxxxxxxxxx > Link: https://lkml.kernel.org/r/20200910070331.3358048-6-davidgow@xxxxxxxxxx > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > --- > mm/kasan/report.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index 5c169aa688fde..90fdb261a5e2d 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -176,7 +176,7 @@ static void kasan_end_report(unsigned long *flags) > pr_err("==================================================================\n"); > add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > spin_unlock_irqrestore(&report_lock, *flags); > - if (panic_on_warn) > + if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) > panic("panic_on_warn set ...\n"); > kasan_enable_current(); Seems this introduced a build failure when CONFIG_KASAN is enabled, as also reported by Sasha[1]. mm/kasan/report.c: In function ‘kasan_end_report’: mm/kasan/report.c:179:16: error: ‘KASAN_BIT_MULTI_SHOT’ undeclared (first use in this function) 179 | if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | ^~~~~~~~~~~~~~~~~~~~ arch/x86/include/asm/bitops.h:342:25: note: in definition of macro ‘test_bit’ 342 | (__builtin_constant_p((nr)) \ | ^~ mm/kasan/report.c:179:16: note: each undeclared identifier is reported only once for each function it appears in 179 | if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | ^~~~~~~~~~~~~~~~~~~~ arch/x86/include/asm/bitops.h:342:25: note: in definition of macro ‘test_bit’ 342 | (__builtin_constant_p((nr)) \ | ^~ mm/kasan/report.c:179:39: error: ‘kasan_flags’ undeclared (first use in this function) 179 | if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | ^~~~~~~~~~~ arch/x86/include/asm/bitops.h:343:30: note: in definition of macro ‘test_bit’ 343 | ? constant_test_bit((nr), (addr)) \ | ^~~~ I confirmed dropping this patch fixes the build failure. It causes a conflict to a following patch[1], but seems it's not that difficult to resolve. I updated kernel/panic.c part of the patch like attached below to resolve the conflict. [1] https://lore.kernel.org/stable/Y9v3G6UantaCo29G@sashalap/ [2] https://lore.kernel.org/stable/20230202052604.179184-13-ebiggers@xxxxxxxxxx/ Thanks, SJ ================================ >8 =========================================== diff --git a/kernel/panic.c b/kernel/panic.c index a078d413042f..08b8adc55b2b 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -125,6 +125,12 @@ void nmi_panic(struct pt_regs *regs, const char *msg) } EXPORT_SYMBOL(nmi_panic); +void check_panic_on_warn(const char *origin) +{ + if (panic_on_warn) + panic("%s: panic_on_warn set ...\n", origin); +} + /** * panic - halt the system * @fmt: The text string to print @@ -540,8 +546,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, if (args) vprintk(args->fmt, args->args); - if (panic_on_warn) - panic("panic_on_warn set ...\n"); + check_panic_on_warn("kernel"); print_modules();
