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Subject: Re: [PATCH v2] Bluetooth: MGMT: Fix uses of bitmap_from_u64
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20220516203539.1708251-1-luiz.dentz@gmail.com>
Date:   Thu, 19 May 2022 20:09:01 +0200
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <4A5486C7-C1E8-41A3-9E7F-E627BBA79503@holtmann.org>
References: <20220516203539.1708251-1-luiz.dentz@gmail.com>
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Precedence: bulk

Hi Luiz,

> bitmap_from_u64 expects at least 8 bytes to be declared since it doesn't
> take any parameter regarding the number of bits causing the following
> warnings:
> 
> In file included from include/linux/cpumask.h:12,
>                 from include/linux/mm_types_task.h:14,
>                 from include/linux/mm_types.h:5,
>                 from include/linux/buildid.h:5,
>                 from include/linux/module.h:14,
>                 from net/bluetooth/mgmt.c:27:
> In function 'bitmap_copy',
>    inlined from 'bitmap_copy_clear_tail' at include/linux/bitmap.h:270:2,
>    inlined from 'bitmap_from_u64' at include/linux/bitmap.h:622:2,
>    inlined from 'set_device_flags' at net/bluetooth/mgmt.c:4534:4:
> include/linux/bitmap.h:261:9: warning: 'memcpy' forming offset [4, 7] is
> out of the bounds [0, 4] of object 'flags' with type
> 'long unsigned int[1]' [-Warray-bounds]
>  261 |         memcpy(dst, src, len);
>      |         ^~~~~~~~~~~~~~~~~~~~~
> In file included from include/linux/kasan-checks.h:5,
>                 from include/asm-generic/rwonce.h:26,
>                 from ./arch/arm/include/generated/asm/rwonce.h:1,
>                 from include/linux/compiler.h:248,
>                 from include/linux/build_bug.h:5,
>                 from include/linux/container_of.h:5,
>                 from include/linux/list.h:5,
>                 from include/linux/module.h:12,
>                 from net/bluetooth/mgmt.c:27:
> net/bluetooth/mgmt.c: In function 'set_device_flags':
> net/bluetooth/mgmt.c:4532:40: note: 'flags' declared here
> 4532 |                         DECLARE_BITMAP(flags, __HCI_CONN_NUM_FLAGS);
>      |                                        ^~~~~
> include/linux/types.h:11:23: note: in definition of macro 'DECLARE_BITMAP'
>   11 |         unsigned long name[BITS_TO_LONGS(bits)]
>      |                       ^~~~
> 
> In order to fix the above this initializes a variable using
> DECLARE_BITMAP with the current_flags and then uses bitmap_subset to
> check if the flags being set are a subset of hdev->conn_flags that way
> all the checks are performed using bitmap APIs and conversion to u32
> only happen when really needed.
> 
> Fixes: a9a347655d22 ("Bluetooth: MGMT: Add conditions for setting HCI_CONN_FLAG_REMOTE_WAKEUP")
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Suggested-by: Yury Norov <yury.norov@gmail.com>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
> net/bluetooth/mgmt.c | 43 ++++++++++++++++++-------------------------
> 1 file changed, 18 insertions(+), 25 deletions(-)

what is up with the kbot issues?

Regards

Marcel