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SubjectRe: [PATCH][next] ath11k: avoid null pointer dereference when pointer band is null
On Sat, Jan 11, 2020 at 12:57:11PM +0100, Marion & Christophe JAILLET wrote:
> Le 11/01/2020 à 10:50, linmiaohe a écrit :
> > Colin Ian King<colin.king@canonical.com> wrote:
> > > From: Colin Ian King<colin.king@canonical.com>
> > >
> > > In the unlikely event that cap->supported_bands has neither WMI_HOST_WLAN_2G_CAP set or WMI_HOST_WLAN_5G_CAP set then pointer band is null and a null dereference occurs when assigning
> > > band->n_iftype_data. Move the assignment to the if blocks to
> > > avoid this. Cleans up static analysis warnings.
> > >
> > > Addresses-Coverity: ("Explicit null dereference")
> > > Fixes: 9f056ed8ee01 ("ath11k: add HE support")
> > > Signed-off-by: Colin Ian King<colin.king@canonical.com>
> > > ---
> > > drivers/net/wireless/ath/ath11k/mac.c | 8 ++++----
> > > 1 file changed, 4 insertions(+), 4 deletions(-)
> > It looks fine for me. Thanks.
> > Reviewed-by: Miaohe Lin<linmiaohe@huawei.com>
> (sorry for incomplete mail and mailing list addresses, my newsreader ate
> them, and I cannot get the list from get_maintainer.pl because my (outdated)
> tree does not have ath11k/...
> I've only including the ones in memory of my mail writer.
>
> Please forward if needed)
>
>
> Hi
>
> Shouldn't there be a
>
> |
>
> - band->n_iftype_data = count; at the end of the patch if the assignment
> is *moved*? Without it, 'band' (as well as 'count') could be un-initialized,
> and lead to memory corruption. Just my 2c. CJ |

You must be looking at different code. There is no uninitialized
variable. The patched code looks like:

drivers/net/wireless/ath/ath11k/mac.c
3520 static void ath11k_mac_setup_he_cap(struct ath11k *ar,
3521 struct ath11k_pdev_cap *cap)
3522 {
3523 struct ieee80211_supported_band *band;
3524 int count;
3525
3526 if (cap->supported_bands & WMI_HOST_WLAN_2G_CAP) {
3527 count = ath11k_mac_copy_he_cap(ar, cap,
3528 ar->mac.iftype[NL80211_BAND_2GHZ],
3529 NL80211_BAND_2GHZ);
3530 band = &ar->mac.sbands[NL80211_BAND_2GHZ];
3531 band->iftype_data = ar->mac.iftype[NL80211_BAND_2GHZ];
3532 band->n_iftype_data = count;
3533 }
3534
3535 if (cap->supported_bands & WMI_HOST_WLAN_5G_CAP) {
3536 count = ath11k_mac_copy_he_cap(ar, cap,
3537 ar->mac.iftype[NL80211_BAND_5GHZ],
3538 NL80211_BAND_5GHZ);
3539 band = &ar->mac.sbands[NL80211_BAND_5GHZ];
3540 band->iftype_data = ar->mac.iftype[NL80211_BAND_5GHZ];
3541 band->n_iftype_data = count;
3542 }
3543 }

regards,
dan carpenter

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