linux-kernel - [PATCH] mm/zsmalloc: do not attempt to free IS

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Date:   Tue, 16 Aug 2022 14:09:06 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Minchan Kim <minchan@...nel.org>
Cc:     Nitin Gupta <ngupta@...are.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH] mm/zsmalloc: do not attempt to free IS_ERR handle

zsmalloc() now returns ERR_PTR values as handles, which zram
accidentally can pass to zs_free(). Another bad scenario
is when zcomp_compress() fails - handle has default -ENOMEM
value, and zs_free() will try to free that "pointer value".

Add the missing check and make sure that zs_free() bails out
when ERR_PTR() is passed to it.

Fixes: c7e6f17b52e9 ("zsmalloc: zs_malloc: return ERR_PTR on failure")
Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 mm/zsmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 99d93a48cbe0..7b3bffc06078 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1487,7 +1487,7 @@ void zs_free(struct zs_pool *pool, unsigned long handle)
 	struct size_class *class;
 	enum fullness_group fullness;
 
-	if (unlikely(!handle))
+	if (IS_ERR_OR_NULL((void *)handle))
 		return;
 
 	/*
-- 
2.37.1.595.g718a3a8f04-goog