linux-kernel - [PATCH] zram: fix potential UAF of zram table

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Message-ID: <20250107065446.86928-1-ryncsn@gmail.com>
Date: Tue,  7 Jan 2025 14:54:46 +0800
From: Kairui Song <ryncsn@...il.com>
To: linux-mm@...ck.org
Cc: Minchan Kim <minchan@...nel.org>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kairui Song <kasong@...cent.com>,
	stable@...r.kernel.org
Subject: [PATCH] zram: fix potential UAF of zram table

From: Kairui Song <kasong@...cent.com>

If zram_meta_alloc failed early, it frees allocated zram->table without
setting it NULL. Which will potentially cause zram_meta_free to access
the table if user reset an failed and uninitialized device.

Fixes: 74363ec674cb ("zram: fix uninitialized ZRAM not releasing backing device")
Cc: <stable@...r.kernel.org>
Signed-off-by: Kairui Song <kasong@...cent.com>
---
 drivers/block/zram/zram_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 5b8e4f4171ab..70ecaee25c20 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1465,6 +1465,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 	zram->mem_pool = zs_create_pool(zram->disk->disk_name);
 	if (!zram->mem_pool) {
 		vfree(zram->table);
+		zram->table = NULL;
 		return false;
 	}
 
-- 
2.47.1