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.
This code was detected with the help of Coccinelle and audited and fixed
manually.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
Signed-off-by: Len Baker <[email protected]>
---
Changelog v1 -> v2
- Rebase against v5.15-rc2
- Remove the unnecessary "size" variable (Gustavo A. R. Silva).
- Update the commit changelog to inform that this code was detected
using a Coccinelle script (Gustavo A. R. Silva).
net/wireless/nl80211.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index bf7cd4752547..fa7ff61c5b07 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -11767,8 +11767,8 @@ static int nl80211_set_cqm_rssi(struct genl_info *info,
if (n_thresholds) {
struct cfg80211_cqm_config *cqm_config;
- 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);
if (!cqm_config) {
err = -ENOMEM;
goto unlock;
@@ -11777,7 +11777,8 @@ 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 +15082,7 @@ 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