Commit 96805674 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Fix bpf_prog_pack for multi-node setup 



module_alloc requires num_online_nodes * PMD_SIZE to allocate huge pages.
bpf_prog_pack uses pack of size num_online_nodes * PMD_SIZE.
OTOH, module_alloc returns addresses that are PMD_SIZE aligned (instead of
num_online_nodes * PMD_SIZE aligned). Therefore, PMD_MASK should be used
to calculate pack_ptr in bpf_prog_pack_free().

Fixes: ef078600 ("bpf: Select proper size for bpf_prog_pack")
Reported-by: default avatar <syzbot+c946805b5ce6ab87df0b@syzkaller.appspotmail.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220321180009.1944482-2-song@kernel.org
parent d56c9fe6

kernel/bpf/core.c

+7 −2
Original line number Diff line number Diff line
@@ -829,6 +829,7 @@ struct bpf_prog_pack { 
#define BPF_PROG_SIZE_TO_NBITS(size)	(round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE)



static size_t bpf_prog_pack_size = -1;

static size_t bpf_prog_pack_mask = -1;



static int bpf_prog_chunk_count(void)

{
@@ -850,8 +851,12 @@ static size_t select_bpf_prog_pack_size(void) 
	/* Test whether we can get huge pages. If not just use PAGE_SIZE

	 * packs.

	 */

	if (!ptr || !is_vm_area_hugepages(ptr))

	if (!ptr || !is_vm_area_hugepages(ptr)) {

		size = PAGE_SIZE;

		bpf_prog_pack_mask = PAGE_MASK;

	} else {

		bpf_prog_pack_mask = PMD_MASK;

	}



	vfree(ptr);

	return size;
@@ -935,7 +940,7 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr) 
		goto out;

	}



	pack_ptr = (void *)((unsigned long)hdr & ~(bpf_prog_pack_size - 1));

	pack_ptr = (void *)((unsigned long)hdr & bpf_prog_pack_mask);



	list_for_each_entry(tmp, &pack_list, list) {

		if (tmp->ptr == pack_ptr) {