From: Zqiang <qiang1.zhang@xxxxxxxxx> Subject: kasan: prevent cpu_quarantine corruption when CPU offline and cache shrink occur at same time kasan_quarantine_remove_cache() is called in kmem_cache_shrink()/ destroy(). The kasan_quarantine_remove_cache() call is protected by cpuslock in kmem_cache_destroy() to ensure serialization with kasan_cpu_offline(). However the kasan_quarantine_remove_cache() call is not protected by cpuslock in kmem_cache_shrink(). When a CPU is going offline and cache shrink occurs at same time, the cpu_quarantine may be corrupted by interrupt (per_cpu_remove_cache operation). So add a cpu_quarantine offline flags check in per_cpu_remove_cache(). [akpm@xxxxxxxxxxxxxxxxxxxx: add comment, per Zqiang] Link: https://lkml.kernel.org/r/20220414025925.2423818-1-qiang1.zhang@xxxxxxxxx Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx> Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/quarantine.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/mm/kasan/quarantine.c~kasan-prevent-cpu_quarantine-corruption-when-cpu-offline-and-cache-shrink-occur-at-same-time +++ a/mm/kasan/quarantine.c @@ -315,6 +315,13 @@ static void per_cpu_remove_cache(void *a struct qlist_head *q; q = this_cpu_ptr(&cpu_quarantine); + /* + * Ensure the ordering between the writing to q->offline and + * per_cpu_remove_cache. Prevent cpu_quarantine from being corrupted + * by interrupt. + */ + if (READ_ONCE(q->offline)) + return; qlist_move_cache(q, &to_free, cache); qlist_free_all(&to_free, cache); } _
