Messages in this thread | | | Date | Wed, 27 Mar 2024 15:23:32 -0600 | Subject | Re: [PATCH][next] wifi: cfg80211: Use __counted_by() in struct wmi_start_scan_cmd and avoid -Wfamnae warning | From | "Gustavo A. R. Silva" <> |
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>> - memset(&cmd, 0, sizeof(cmd)); >> - cmd.cmd.scan_type = WMI_ACTIVE_SCAN; >> - cmd.cmd.num_channels = 0; >> + memset(cmd, 0, sizeof(*cmd)); > > Isn't this unnecessary since DEFINE_FLEX() logic "{ .obj.COUNTER = COUNT, }" > should result in everything else being zeroed? > > And if that isn't sufficient, DEFINE_FLEX() itself says we should "Use > __struct_size(@NAME) to get compile-time size of it afterwards" > > Note the current memset won't zero the flex array and hence if the actual > number of channels is less than 4 then kernel stack contents could be exposed > to firmware.
Yes, that's correct. The current memset() will only zero out a total of sizeof(struct wmi_start_scan_cmd) bytes, which of course doesn't include the flex-array member.
Thanks for the review, I'll remove that line!
-- Gustavo
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