| Message ID | 20210919114040.41522-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | nl80211: prefer struct_size over open coded arithmetic | expand |
On 9/19/21 06:40, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() functions. > > Also, take the opportunity to refactor the memcpy() call to use the > flex_array_size() helper. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> > --- > net/wireless/nl80211.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c > index bf7cd4752547..b56856349ced 100644 > --- a/net/wireless/nl80211.c > +++ b/net/wireless/nl80211.c > @@ -11766,9 +11766,10 @@ static int nl80211_set_cqm_rssi(struct genl_info *info, > wdev_lock(wdev); > if (n_thresholds) { > struct cfg80211_cqm_config *cqm_config; > + size_t size = struct_size(cqm_config, rssi_thresholds, > + n_thresholds); > > - cqm_config = kzalloc(sizeof(struct cfg80211_cqm_config) + > - n_thresholds * sizeof(s32), GFP_KERNEL); > + cqm_config = kzalloc(size, GFP_KERNEL); I don't think variable _size_ is needed here; this is just fine: - cqm_config = kzalloc(sizeof(struct cfg80211_cqm_config) + - n_thresholds * sizeof(s32), GFP_KERNEL); + cqm_config = kzalloc(struct_size(cqm_config, rssi_thresholds, + n_thresholds), GFP_KERNEL); Thanks -- Gustavo > if (!cqm_config) { > err = -ENOMEM; > goto unlock; > @@ -11777,7 +11778,8 @@ static int nl80211_set_cqm_rssi(struct genl_info *info, > cqm_config->rssi_hyst = hysteresis; > cqm_config->n_rssi_thresholds = n_thresholds; > memcpy(cqm_config->rssi_thresholds, thresholds, > - n_thresholds * sizeof(s32)); > + flex_array_size(cqm_config, rssi_thresholds, > + n_thresholds)); > > wdev->cqm_config = cqm_config; > } > @@ -15081,9 +15083,7 @@ static int nl80211_set_sar_specs(struct sk_buff *skb, struct genl_info *info) > if (specs > rdev->wiphy.sar_capa->num_freq_ranges) > return -EINVAL; > > - sar_spec = kzalloc(sizeof(*sar_spec) + > - specs * sizeof(struct cfg80211_sar_sub_specs), > - GFP_KERNEL); > + sar_spec = kzalloc(struct_size(sar_spec, sub_specs, specs), GFP_KERNEL); > if (!sar_spec) > return -ENOMEM; > > -- > 2.25.1 >
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index bf7cd4752547..b56856349ced 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -11766,9 +11766,10 @@ static int nl80211_set_cqm_rssi(struct genl_info *info, wdev_lock(wdev); if (n_thresholds) { struct cfg80211_cqm_config *cqm_config; + size_t size = struct_size(cqm_config, rssi_thresholds, + n_thresholds); - cqm_config = kzalloc(sizeof(struct cfg80211_cqm_config) + - n_thresholds * sizeof(s32), GFP_KERNEL); + cqm_config = kzalloc(size, GFP_KERNEL); if (!cqm_config) { err = -ENOMEM; goto unlock; @@ -11777,7 +11778,8 @@ static int nl80211_set_cqm_rssi(struct genl_info *info, cqm_config->rssi_hyst = hysteresis; cqm_config->n_rssi_thresholds = n_thresholds; memcpy(cqm_config->rssi_thresholds, thresholds, - n_thresholds * sizeof(s32)); + flex_array_size(cqm_config, rssi_thresholds, + n_thresholds)); wdev->cqm_config = cqm_config; } @@ -15081,9 +15083,7 @@ static int nl80211_set_sar_specs(struct sk_buff *skb, struct genl_info *info) if (specs > rdev->wiphy.sar_capa->num_freq_ranges) return -EINVAL; - sar_spec = kzalloc(sizeof(*sar_spec) + - specs * sizeof(struct cfg80211_sar_sub_specs), - GFP_KERNEL); + sar_spec = kzalloc(struct_size(sar_spec, sub_specs, specs), GFP_KERNEL); if (!sar_spec) return -ENOMEM;
As noted in the "Deprecated Interfaces, Language Features, Attributes, and Conventions" documentation [1], size calculations (especially multiplication) should not be performed in memory allocator (or similar) function arguments due to the risk of them overflowing. This could lead to values wrapping around and a smaller allocation being made than the caller was expecting. Using those allocations could lead to linear overflows of heap memory and other misbehaviors. So, use the struct_size() helper to do the arithmetic instead of the argument "size + count * size" in the kzalloc() functions. Also, take the opportunity to refactor the memcpy() call to use the flex_array_size() helper. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <len.baker@gmx.com> --- net/wireless/nl80211.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) -- 2.25.1