Search Linux Wireless

Re: [PATCH 1/2] [RESEND] wifi: carl9170: re-fix fortified-memset warning

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 3/28/24 2:55 PM, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>

The carl9170_tx_release() function sometimes triggers a fortified-memset
warning in my randconfig builds:

In file included from include/linux/string.h:254,
                  from drivers/net/wireless/ath/carl9170/tx.c:40:
In function 'fortify_memset_chk',
     inlined from 'carl9170_tx_release' at drivers/net/wireless/ath/carl9170/tx.c:283:2,
     inlined from 'kref_put' at include/linux/kref.h:65:3,
     inlined from 'carl9170_tx_put_skb' at drivers/net/wireless/ath/carl9170/tx.c:342:9:
include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
   493 |                         __write_overflow_field(p_size_field, size);

Kees previously tried to avoid this by using memset_after(), but it seems
this does not fully address the problem. I noticed that the memset_after()
here is done on a different part of the union (status) than the original
cast was from (rate_driver_data), which may confuse the compiler.

Unfortunately, the memset_after() trick does not work on driver_rates[]
because that is part of an anonymous struct, and I could not get
struct_group() to do this either. Using two separate memset() calls
on the two members does address the warning though.

Fixes: fb5f6a0e8063b ("mac80211: Use memset_after() to clear tx status")
Link: https://lore.kernel.org/lkml/20230623152443.2296825-1-arnd@xxxxxxxxxx/
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Sure... though I think AI-supported compilers will in the future nag about
this again. Oh well!

Acked-by: Christian Lamparter <chunkeey@xxxxxxxxx>


---
I found this while testing randconfig builds, a .config that shows this
for me is at https://pastebin.com/yWFKvZYu

Sorry I failed to follow up to Kees' request for a reproducer when
I posted this last year.
---
  drivers/net/wireless/ath/carl9170/tx.c | 3 ++-
  1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c
index e902ca80eba7..0226c31a6cae 100644
--- a/drivers/net/wireless/ath/carl9170/tx.c
+++ b/drivers/net/wireless/ath/carl9170/tx.c
@@ -280,7 +280,8 @@ static void carl9170_tx_release(struct kref *ref)
  	 * carl9170_tx_fill_rateinfo() has filled the rate information
  	 * before we get to this point.
  	 */
-	memset_after(&txinfo->status, 0, rates);
+	memset(&txinfo->pad, 0, sizeof(txinfo->pad));
+	memset(&txinfo->rate_driver_data, 0, sizeof(txinfo->rate_driver_data));






[Index of Archives]     [Linux Host AP]     [ATH6KL]     [Linux Wireless Personal Area Network]     [Linux Bluetooth]     [Wireless Regulations]     [Linux Netdev]     [Kernel Newbies]     [Linux Kernel]     [IDE]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Hiking]     [MIPS Linux]     [ARM Linux]     [Linux RAID]

  Powered by Linux