linux-kernel - [PATCH 4.14 162/218] ubi: ubi_create_volume: Fix use-after-free when volume creation failed

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Date:   Mon, 13 Jun 2022 12:10:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhihao Cheng <chengzhihao1@...wei.com>,
        Richard Weinberger <richard@....at>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 162/218] ubi: ubi_create_volume: Fix use-after-free when volume creation failed

From: Zhihao Cheng <chengzhihao1@...wei.com>

[ Upstream commit 8c03a1c21d72210f81cb369cc528e3fde4b45411 ]

There is an use-after-free problem for 'eba_tbl' in ubi_create_volume()'s
error handling path:

  ubi_eba_replace_table(vol, eba_tbl)
    vol->eba_tbl = tbl
out_mapping:
  ubi_eba_destroy_table(eba_tbl)   // Free 'eba_tbl'
out_unlock:
  put_device(&vol->dev)
    vol_release
      kfree(tbl->entries)	  // UAF

Fix it by removing redundant 'eba_tbl' releasing.
Fetch a reproducer in [Link].

Fixes: 493cfaeaa0c9b ("mtd: utilize new cdev_device_add helper function")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215965
Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mtd/ubi/vmt.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 8f641448a97a..d32144c0098a 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -315,7 +315,6 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 	ubi->volumes[vol_id] = NULL;
 	ubi->vol_count -= 1;
 	spin_unlock(&ubi->volumes_lock);
-	ubi_eba_destroy_table(eba_tbl);
 out_acc:
 	spin_lock(&ubi->volumes_lock);
 	ubi->rsvd_pebs -= vol->reserved_pebs;
-- 
2.35.1