wireless: mwifiex: fix double free

Commit Message

Tom Rix Oct. 4, 2020, 1:19 p.m. UTC

From: Tom Rix <[e-mail]>

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 <[e-mail]>
---
 drivers/net/wireless/marvell/mwifiex/sdio.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Brian Norris Oct. 5, 2020, 5:58 p.m. UTC | #1

On Sun, Oct 4, 2020 at 6:19 AM <[e-mail]> wrote:
>
> From: Tom Rix <[e-mail]>
>
> clang static analysis reports this problem:
>
> sdio.c:2403:3: warning: Attempt to free released memory
>         kfree(card->mpa_rx.buf);
>         ^~~~~~~~~~~~~~~~~~~~~~~

That's some interesting static analysis for a compiler.

> 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 <[e-mail]>

For whatever it's worth:

Reviewed-by: Brian Norris <[e-mail]>

Kalle Valo Oct. 8, 2020, 10:46 a.m. UTC | #2

[e-mail] wrote:

> From: Tom Rix <[e-mail]>
> 
> 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 <[e-mail]>
> Reviewed-by: Brian Norris <[e-mail]>

Patch applied to wireless-drivers-next.git, thanks.

53708f4fd9cf mwifiex: fix double free

Patch

diff --git a/drivers/net/wireless/marvell/mwifiex/sdio.c b/drivers/net/wireless/marvell/mwifiex/sdio.c
index 69911c728eb1..bde9e4bbfffe 100644
--- a/drivers/net/wireless/marvell/mwifiex/sdio.c
+++ b/drivers/net/wireless/marvell/mwifiex/sdio.c
@@ -2403,6 +2403,8 @@  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;