From: David Gow <davidgow@xxxxxxxxxx> Subject: mm: kasan: do not panic if both panic_on_warn and kasan_multishot set 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). 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: David Gow <davidgow@xxxxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Brendan Higgins <brendanhiggins@xxxxxxxxxx> Tested-by: Andrey Konovalov <andreyknvl@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> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/report.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/kasan/report.c~mm-kasan-do-not-panic-if-both-panic_on_warn-and-kasan_multishot-set +++ a/mm/kasan/report.c @@ -95,7 +95,7 @@ static void end_report(unsigned long *fl 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)) { /* * This thread may hit another WARN() in the panic path. * Resetting this prevents additional WARN() from panicking the _
