Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
a backtrace caused by the following field-spanning error:
memcpy: detected field-spanning write (size 120) of single field
"¶ms_le->channel_list[0]" at
drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
Fix this by replacing the channel_list[1] declaration at the end of
the struct with a flexible array declaration.
Most users of struct brcmf_scan_params_le calculate the size to alloc
using the size of the non flex-array part of the struct + needed extra
space, so they do not care about sizeof(struct brcmf_scan_params_le).
brcmf_notify_escan_complete() however uses the struct on the stack,
expecting there to be room for at least 1 entry in the channel-list
to store the special -1 abort channel-id.
To make this work use an anonymous union with a padding member
added + the actual channel_list flexible array.
Cc: Kees Cook <[email protected]>
Signed-off-by: Hans de Goede <[email protected]>
---
.../net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
index 792adaf880b4..bece26741d3a 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
@@ -398,7 +398,12 @@ struct brcmf_scan_params_le {
* fixed parameter portion is assumed, otherwise
* ssid in the fixed portion is ignored
*/
- __le16 channel_list[1]; /* list of chanspecs */
+ union {
+ __le16 padding; /* Reserve space for at least 1 entry for abort
+ * which uses an on stack brcmf_scan_params_le
+ */
+ DECLARE_FLEX_ARRAY(__le16, channel_list); /* chanspecs */
+ };
};
struct brcmf_scan_params_v2_le {
--
2.41.0
On Sat, Jul 29, 2023 at 04:05:00PM +0200, Hans de Goede wrote:
> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
> a backtrace caused by the following field-spanning error:
>
> memcpy: detected field-spanning write (size 120) of single field
> "¶ms_le->channel_list[0]" at
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>
> Fix this by replacing the channel_list[1] declaration at the end of
> the struct with a flexible array declaration.
>
> Most users of struct brcmf_scan_params_le calculate the size to alloc
> using the size of the non flex-array part of the struct + needed extra
> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>
> brcmf_notify_escan_complete() however uses the struct on the stack,
> expecting there to be room for at least 1 entry in the channel-list
> to store the special -1 abort channel-id.
>
> To make this work use an anonymous union with a padding member
> added + the actual channel_list flexible array.
>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Hans de Goede <[email protected]>
Looks good to me; it's consistent with how similar 1-element arrays
with sensitive structure sizes have been updated lately. Thanks for
the investigation!
Reviewed-by: Kees Cook <[email protected]>
-Kees
--
Kees Cook
Hans de Goede <[email protected]> wrote:
> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
> a backtrace caused by the following field-spanning error:
>
> memcpy: detected field-spanning write (size 120) of single field
> "¶ms_le->channel_list[0]" at
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>
> Fix this by replacing the channel_list[1] declaration at the end of
> the struct with a flexible array declaration.
>
> Most users of struct brcmf_scan_params_le calculate the size to alloc
> using the size of the non flex-array part of the struct + needed extra
> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>
> brcmf_notify_escan_complete() however uses the struct on the stack,
> expecting there to be room for at least 1 entry in the channel-list
> to store the special -1 abort channel-id.
>
> To make this work use an anonymous union with a padding member
> added + the actual channel_list flexible array.
>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Hans de Goede <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
Does the driver still work even if this warning is printed? I'm wondering
should I take this to wireless or wireless-next. Also a review from Broadcom
would be really good.
What about a Fixes tag?
--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
Hi,
On 8/1/23 16:37, Kalle Valo wrote:
> Hans de Goede <[email protected]> wrote:
>
>> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
>> a backtrace caused by the following field-spanning error:
>>
>> memcpy: detected field-spanning write (size 120) of single field
>> "¶ms_le->channel_list[0]" at
>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>>
>> Fix this by replacing the channel_list[1] declaration at the end of
>> the struct with a flexible array declaration.
>>
>> Most users of struct brcmf_scan_params_le calculate the size to alloc
>> using the size of the non flex-array part of the struct + needed extra
>> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>>
>> brcmf_notify_escan_complete() however uses the struct on the stack,
>> expecting there to be room for at least 1 entry in the channel-list
>> to store the special -1 abort channel-id.
>>
>> To make this work use an anonymous union with a padding member
>> added + the actual channel_list flexible array.
>>
>> Cc: Kees Cook <[email protected]>
>> Signed-off-by: Hans de Goede <[email protected]>
>> Reviewed-by: Kees Cook <[email protected]>
>
> Does the driver still work even if this warning is printed? I'm wondering
> should I take this to wireless or wireless-next. Also a review from Broadcom
> would be really good.
It works fine, but it logs an oops / backtrace.
Note I did test the patch on a device where the warning was triggered and the warning is gone and wifi association still works.
So there is a slight preference to get this as a fix into 6.5 from my side.
> What about a Fixes tag?
This is caused by the new field-spanning wtire checks enabled recently, so there is not really a brcmfmac commit to point to as the culprit.
Regards,
Hans
Hans de Goede <[email protected]> writes:
> Hi,
>
> On 8/1/23 16:37, Kalle Valo wrote:
>> Hans de Goede <[email protected]> wrote:
>>
>>> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
>>> a backtrace caused by the following field-spanning error:
>>>
>>> memcpy: detected field-spanning write (size 120) of single field
>>> "¶ms_le->channel_list[0]" at
>>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>>>
>>> Fix this by replacing the channel_list[1] declaration at the end of
>>> the struct with a flexible array declaration.
>>>
>>> Most users of struct brcmf_scan_params_le calculate the size to alloc
>>> using the size of the non flex-array part of the struct + needed extra
>>> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>>>
>>> brcmf_notify_escan_complete() however uses the struct on the stack,
>>> expecting there to be room for at least 1 entry in the channel-list
>>> to store the special -1 abort channel-id.
>>>
>>> To make this work use an anonymous union with a padding member
>>> added + the actual channel_list flexible array.
>>>
>>> Cc: Kees Cook <[email protected]>
>>> Signed-off-by: Hans de Goede <[email protected]>
>>> Reviewed-by: Kees Cook <[email protected]>
>>
>> Does the driver still work even if this warning is printed? I'm wondering
>> should I take this to wireless or wireless-next. Also a review from Broadcom
>> would be really good.
>
> It works fine, but it logs an oops / backtrace.
I'll add that info to the commit log.
> Note I did test the patch on a device where the warning was triggered
> and the warning is gone and wifi association still works.
>
> So there is a slight preference to get this as a fix into 6.5 from my side.
I'll queue this wireless then. But I really would like to Broadcom take
a look at this in case we are missing something.
>> What about a Fixes tag?
>
> This is caused by the new field-spanning wtire checks enabled
> recently, so there is not really a brcmfmac commit to point to as the
> culprit.
Ok.
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
On Tue, Aug 1, 2023 at 7:55 AM Kalle Valo <[email protected]> wrote:
>
> Hans de Goede <[email protected]> writes:
>
> > Hi,
> >
> > On 8/1/23 16:37, Kalle Valo wrote:
> >> Hans de Goede <[email protected]> wrote:
> >>
> >>> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
> >>> a backtrace caused by the following field-spanning error:
> >>>
> >>> memcpy: detected field-spanning write (size 120) of single field
> >>> "¶ms_le->channel_list[0]" at
> >>> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
> >>>
> >>> Fix this by replacing the channel_list[1] declaration at the end of
> >>> the struct with a flexible array declaration.
> >>>
> >>> Most users of struct brcmf_scan_params_le calculate the size to alloc
> >>> using the size of the non flex-array part of the struct + needed extra
> >>> space, so they do not care about sizeof(struct brcmf_scan_params_le).
> >>>
> >>> brcmf_notify_escan_complete() however uses the struct on the stack,
> >>> expecting there to be room for at least 1 entry in the channel-list
> >>> to store the special -1 abort channel-id.
> >>>
> >>> To make this work use an anonymous union with a padding member
> >>> added + the actual channel_list flexible array.
> >>>
> >>> Cc: Kees Cook <[email protected]>
> >>> Signed-off-by: Hans de Goede <[email protected]>
> >>> Reviewed-by: Kees Cook <[email protected]>
Looks good to me, thanks for taking care of it.
Reviewed-by: Franky Lin <[email protected]>
Hans de Goede <[email protected]> wrote:
> Using brcmfmac with 6.5-rc3 on a brcmfmac43241b4-sdio triggers
> a backtrace caused by the following field-spanning warning:
>
> memcpy: detected field-spanning write (size 120) of single field
> "¶ms_le->channel_list[0]" at
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1072 (size 2)
>
> The driver still works after this warning. The warning was introduced by the
> new field-spanning write checks which were enabled recently.
>
> Fix this by replacing the channel_list[1] declaration at the end of
> the struct with a flexible array declaration.
>
> Most users of struct brcmf_scan_params_le calculate the size to alloc
> using the size of the non flex-array part of the struct + needed extra
> space, so they do not care about sizeof(struct brcmf_scan_params_le).
>
> brcmf_notify_escan_complete() however uses the struct on the stack,
> expecting there to be room for at least 1 entry in the channel-list
> to store the special -1 abort channel-id.
>
> To make this work use an anonymous union with a padding member
> added + the actual channel_list flexible array.
>
> Cc: Kees Cook <[email protected]>
> Signed-off-by: Hans de Goede <[email protected]>
> Reviewed-by: Kees Cook <[email protected]>
> Reviewed-by: Franky Lin <[email protected]>
Patch applied to wireless.git, thanks.
16e455a465fc wifi: brcmfmac: Fix field-spanning write in brcmf_scan_params_v2_to_v1()
--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches