linux-kernel - Re: [PATCH] zram: fix null dereference of handle

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Date:   Tue, 19 Sep 2017 19:21:25 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, kernel-team <kernel-team@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH] zram: fix null dereference of handle

Minchan,

I just ran across it [because I had a bug to analize where this
part was involved]. I'd really prefer the kernel to BUG_ON immediately
instead of dying in agony.

can we, please, return BUG_ON() back?

there is no point in trying to save the kernel once it did that type
of violation.

---

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 7c38e850a8fc..685049a9048d 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1349,7 +1349,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
         * pools/users, we can't allow mapping in interrupt context
         * because it can corrupt another users mappings.
         */
-       WARN_ON_ONCE(in_interrupt());
+       BUG_ON(in_interrupt());
 
        /* From now on, migration cannot move the object */
        pin_tag(handle);