On Mon, Aug 16, 2021 at 2:43 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On 8/16/21 6:48 PM, Stanislav Fomichev wrote: > > Use kvmalloc/kvfree for temporary value when looking up a map. > > kmalloc might not be sufficient for percpu maps where the value is big. > > > > Can be reproduced with netcnt test on qemu with "-smp 255". > > > > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > > --- > > kernel/bpf/syscall.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index 9a2068e39d23..ae0b1c1c8ece 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -1076,7 +1076,7 @@ static int map_lookup_elem(union bpf_attr *attr) > > value_size = bpf_map_value_size(map); > > > > err = -ENOMEM; > > - value = kmalloc(value_size, GFP_USER | __GFP_NOWARN); > > + value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN); > > if (!value) > > goto free_key; > > What about other cases like map_update_elem(), shouldn't they be adapted > similarly? And in the same vein (with keys potentially being big as well), should we switch __bpf_copy_key() to use vmemdup_user() instead of memdup_user()? > > Thanks, > Daniel
