linux-kernel - [PATCH 2/2] ubi: Fix unreferenced object reported by kmemleak in ubi_resize

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Message-ID: <20221021102157.1341807-3-lizetao1@huawei.com>
Date:   Fri, 21 Oct 2022 18:21:57 +0800
From:   Li Zetao <lizetao1@...wei.com>
To:     <richard@....at>, <miquel.raynal@...tlin.com>, <vigneshr@...com>,
        <dedekind@...utronix.de>, <haver@...t.ibm.com>,
        <bbrezillon@...nel.org>
CC:     <lizetao1@...wei.com>, <boris.brezillon@...e-electrons.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] ubi: Fix unreferenced object reported by kmemleak in ubi_resize_volume()

There is a memory leaks problem reported by kmemleak:

unreferenced object 0xffff888102007a00 (size 128):
  comm "ubirsvol", pid 32090, jiffies 4298464136 (age 2361.231s)
  hex dump (first 32 bytes):
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
[<ffffffff8176cecd>] __kmalloc+0x4d/0x150
[<ffffffffa02a9a36>] ubi_eba_create_table+0x76/0x170 [ubi]
[<ffffffffa029764e>] ubi_resize_volume+0x1be/0xbc0 [ubi]
[<ffffffffa02a3321>] ubi_cdev_ioctl+0x701/0x1850 [ubi]
[<ffffffff81975d2d>] __x64_sys_ioctl+0x11d/0x170
[<ffffffff83c142a5>] do_syscall_64+0x35/0x80
[<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

This is due to a mismatch between create and destroy interfaces, and
in detail that "new_eba_tbl" created by ubi_eba_create_table() but
destroyed by kfree(), while will causing "new_eba_tbl->entries" not
freed.

Fix it by replacing kfree(new_eba_tbl) with
ubi_eba_destroy_table(new_eba_tbl)

Fixes: 799dca34ac54 ("UBI: hide EBA internals")
Signed-off-by: Li Zetao <lizetao1@...wei.com>
---
 drivers/mtd/ubi/vmt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 74637575346e..9fbc64b997ce 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -515,7 +515,7 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 	return err;

 out_free:
-	kfree(new_eba_tbl);
+	ubi_eba_destroy_table(new_eba_tbl);
 	return err;
 }

-- 
2.31.1