netdev - [BUG] net: brocade: bna: Possible concurrency use-after-free bugs

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Date:   Wed, 26 Dec 2018 22:35:45 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     rasesh.mody@...ium.com, sudarsana.kalluru@...ium.com,
        Dept-GELinuxNICDev@...ium.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] net: brocade: bna: Possible concurrency use-after-free bugs

In drivers/net/ethernet/brocade/bna/bnad_debugfs.c, the functions 
bnad_debugfs_read_regrd() and bnad_debugfs_write_regrd() may be 
concurrently executed.

bnad_debugfs_read_regrd()
   line 293: if (!bnad->regdata)
   line 297: simple_read_from_buffer(..., bnad->regdata, ...)
   line 300: kfree(bnad->regdata)

bnad_debugfs_write_regrd()
   line 335: kfree(bnad->regdata)
   line 338: kfree(bnad->regdata)
   line 357: regbuf =  (u32 *)bnad->regdata

All these accesses to bnad->regdata are not protected by any lock.
Thus, possible concurrency use-after-free bugs may occur.

A possible fixing way is to use a lock to protect these accesses.
I am not sure about this way, so I only report the bugs.

Best wishes,
Jia-Ju Bai