From 78d4dccf1601fa4ee30d2946fbbba48723b9b3a7 Mon Sep 17 00:00:00 2001 From: Zqiang Date: Wed, 27 Apr 2022 12:41:56 -0700 Subject: [PATCH] kasan: prevent cpu_quarantine corruption when CPU offline and cache shrink occur at same time commit 31fa985b4196f8a66f027672e9bf2b81fea0417c upstream. 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@linux-foundation.org: add comment, per Zqiang] Link: https://lkml.kernel.org/r/20220414025925.2423818-1-qiang1.zhang@intel.com Signed-off-by: Zqiang Reviewed-by: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/kasan/quarantine.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index 0e3f8494628f..622193846b6b 100644 --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -299,6 +299,13 @@ static void per_cpu_remove_cache(void *arg) 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); }