Hang Zhang <zh.nvgt@xxxxxxxxx> wrote: > A previous commit 4f68ef64cd7f ("cw1200: Fix concurrency > use-after-free bugs in cw1200_hw_scan()") tried to fix a seemingly > use-after-free bug between cw1200_bss_info_changed() and > cw1200_hw_scan(), where the former frees a sk_buff pointed > to by frame.skb, and the latter accesses the sk_buff > pointed to by frame.skb. However, this issue should be a > false alarm because: > > (1) "frame.skb" is not a shared variable between the above > two functions, because "frame" is a local function variable, > each of the two functions has its own local "frame" - they > just happen to have the same variable name. > > (2) the sk_buff(s) pointed to by these two "frame.skb" are > also two different object instances, they are individually > allocated by different dev_alloc_skb() within the two above > functions. To free one object instance will not invalidate > the access of another different one. > > Based on these facts, the previous commit should be unnecessary. > Moreover, it also introduced a missing unlock which was > addressed in a subsequent commit 51c8d24101c7 ("cw1200: fix missing > unlock on error in cw1200_hw_scan()"). Now that the > original use-after-free is unreal, these two commits should > be reverted. This patch performs the reversion. > > Fixes: 4f68ef64cd7f ("cw1200: Fix concurrency use-after-free bugs in cw1200_hw_scan()") > Fixes: 51c8d24101c7 ("cw1200: fix missing unlock on error in cw1200_hw_scan()") > Signed-off-by: Hang Zhang <zh.nvgt@xxxxxxxxx> > Acked-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx> Patch applied to wireless-drivers-next.git, thanks. 3f60f4685699 cw1200: Revert unnecessary patches that fix unreal use-after-free bugs -- https://patchwork.kernel.org/project/linux-wireless/patch/20210521223238.25020-1-zh.nvgt@xxxxxxxxx/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches