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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Tom Rix <trix@redhat.com>,
        Brian Norris <briannorris@chromium.org>,
        Kalle Valo <kvalo@codeaurora.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 051/112] mwifiex: fix double free
Date:   Tue, 27 Oct 2020 14:49:21 +0100
Message-Id: <20201027134902.981414532@linuxfoundation.org>
In-Reply-To: <20201027134900.532249571@linuxfoundation.org>
References: <20201027134900.532249571@linuxfoundation.org>
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From: Tom Rix <trix@redhat.com>

[ Upstream commit 53708f4fd9cfe389beab5c8daa763bcd0e0b4aef ]

clang static analysis reports this problem:

sdio.c:2403:3: warning: Attempt to free released memory
        kfree(card->mpa_rx.buf);
        ^~~~~~~~~~~~~~~~~~~~~~~

When mwifiex_init_sdio() fails in its first call to
mwifiex_alloc_sdio_mpa_buffer, it falls back to calling it
again.  If the second alloc of mpa_tx.buf fails, the error
handler will try to free the old, previously freed mpa_rx.buf.
Reviewing the code, it looks like a second double free would
happen with mwifiex_cleanup_sdio().

So set both pointers to NULL when they are freed.

Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201004131931.29782-1-trix@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/mwifiex/sdio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/mwifiex/sdio.c b/drivers/net/wireless/mwifiex/sdio.c
index 78a8474e1a3dc..abfe4e8700ed3 100644
--- a/drivers/net/wireless/mwifiex/sdio.c
+++ b/drivers/net/wireless/mwifiex/sdio.c
@@ -1928,6 +1928,8 @@ static int mwifiex_alloc_sdio_mpa_buffers(struct mwifiex_adapter *adapter,
 		kfree(card->mpa_rx.buf);
 		card->mpa_tx.buf_size = 0;
 		card->mpa_rx.buf_size = 0;
+		card->mpa_tx.buf = NULL;
+		card->mpa_rx.buf = NULL;
 	}
 
 	return ret;
-- 
2.25.1