Toshiaki Makita <toshiaki.makita1@xxxxxxxxx> writes: > dev_map_free() waits for flush_needed bitmap to be empty in order to > ensure all flush operations have completed before freeing its entries. > However the corresponding clear_bit() was called before using the > entries, so the entries could be used after free. > > All access to the entries needs to be done before clearing the bit. > It seems commit a5e2da6e9787 ("bpf: netdev is never null in > __dev_map_flush") accidentally changed the clear_bit() and memory access > order. > > Note that the problem happens only in __dev_map_flush(), not in > dev_map_flush_old(). dev_map_flush_old() is called only after nulling > out the corresponding netdev_map entry, so dev_map_free() never frees > the entry thus no such race happens there. > > Fixes: a5e2da6e9787 ("bpf: netdev is never null in __dev_map_flush") > Signed-off-by: Toshiaki Makita <toshiaki.makita1@xxxxxxxxx> I recently posted a patch[0] that gets rid of the bitmap entirely, so I think you can drop this one... -Toke [0] https://lore.kernel.org/netdev/156042464148.25684.11881534392137955942.stgit@alrua-x1/
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