Toke Høiland-Jørgensen <toke@xxxxxxxxxx> writes: > 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... Alternatively, since this entire series should probably go to stable, I can respin mine on top of it? -Toke
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