The lkp kernel test robot reports, with CONFIG_DEBUG_PREEMPT enabled:

[ 165.316525] BUG: using smp_processor_id() in preemptible [00000000] code: nft/6247 [ 165.319547] caller is nft_pipapo_insert+0x464/0x610 [nf_tables] [ 165.321846] CPU: 1 PID: 6247 Comm: nft Not tainted 5.6.0-rc5-01595-ge32a4dc6512ce3 #1 [ 165.332128] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 165.334892] Call Trace: [ 165.336435] dump_stack+0x8f/0xcb [ 165.338128] debug_smp_processor_id+0xb2/0xc0 [ 165.340117] nft_pipapo_insert+0x464/0x610 [nf_tables] [ 165.342290] ? nft_trans_alloc_gfp+0x1c/0x60 [nf_tables] [ 165.344420] ? rcu_read_lock_sched_held+0x52/0x80 [ 165.346460] ? nft_trans_alloc_gfp+0x1c/0x60 [nf_tables] [ 165.348543] ? __mmu_interval_notifier_insert+0xa0/0xf0 [ 165.350629] nft_add_set_elem+0x5ff/0xa90 [nf_tables] [ 165.352699] ? __lock_acquire+0x241/0x1400 [ 165.354573] ? __lock_acquire+0x241/0x1400 [ 165.356399] ? reacquire_held_locks+0x12f/0x200 [ 165.358384] ? nf_tables_valid_genid+0x1f/0x40 [nf_tables] [ 165.360502] ? nla_strcmp+0x10/0x50 [ 165.362199] ? nft_table_lookup+0x4f/0xa0 [nf_tables] [ 165.364217] ? nla_strcmp+0x10/0x50 [ 165.365891] ? nf_tables_newsetelem+0xd5/0x150 [nf_tables] [ 165.367997] nf_tables_newsetelem+0xd5/0x150 [nf_tables] [ 165.370083] nfnetlink_rcv_batch+0x4fd/0x790 [nfnetlink] [ 165.372205] ? __lock_acquire+0x241/0x1400 [ 165.374058] ? __nla_validate_parse+0x57/0x8a0 [ 165.375989] ? cap_inode_getsecurity+0x230/0x230 [ 165.377954] ? security_capable+0x38/0x50 [ 165.379795] nfnetlink_rcv+0x11d/0x140 [nfnetlink] [ 165.381779] netlink_unicast+0x1b2/0x280 [ 165.383612] netlink_sendmsg+0x351/0x470 [ 165.385439] sock_sendmsg+0x5b/0x60 [ 165.387133] ____sys_sendmsg+0x200/0x280 [ 165.388871] ? copy_msghdr_from_user+0xd9/0x160 [ 165.390805] ___sys_sendmsg+0x88/0xd0 [ 165.392524] ? __might_fault+0x3e/0x90 [ 165.394273] ? sock_getsockopt+0x3d5/0xbb0 [ 165.396021] ? __handle_mm_fault+0x545/0x6a0 [ 165.397822] ? find_held_lock+0x2d/0x90 [ 165.399593] ? __sys_sendmsg+0x5e/0xa0 [ 165.401338] __sys_sendmsg+0x5e/0xa0 [ 165.402979] do_syscall_64+0x60/0x280 [ 165.404680] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 165.406621] RIP: 0033:0x7ff1fa46e783 [ 165.408299] Code: c7 c0 ff ff ff ff eb bb 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 89 54 24 1c 48 [ 165.414163] RSP: 002b:00007ffedf59ea78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 165.416804] RAX: ffffffffffffffda RBX: 00007ffedf59fc60 RCX: 00007ff1fa46e783 [ 165.419419] RDX: 0000000000000000 RSI: 00007ffedf59fb10 RDI: 0000000000000005 [ 165.421886] RBP: 00007ffedf59fc10 R08: 00007ffedf59ea54 R09: 0000000000000001 [ 165.424445] R10: 00007ff1fa630c6c R11: 0000000000000246 R12: 0000000000020000 [ 165.426954] R13: 0000000000000280 R14: 0000000000000005 R15: 00007ffedf59ea90

Disable preemption before accessing the lookup scratch area in nft_pipapo_insert().

Reported-by: kernel test robot lkp@intel.com Analysed-by: Florian Westphal fw@strlen.de Cc: stable@vger.kernel.org # 5.6.x Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges") Signed-off-by: Stefano Brivio sbrivio@redhat.com --- net/netfilter/nft_set_pipapo.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c index 8b5acc6910fd..8c04388296b0 100644 --- a/net/netfilter/nft_set_pipapo.c +++ b/net/netfilter/nft_set_pipapo.c @@ -1242,7 +1242,9 @@ static int nft_pipapo_insert(const struct net *net, const struct nft_set *set, end += NFT_PIPAPO_GROUPS_PADDED_SIZE(f); }

- if (!*this_cpu_ptr(m->scratch) || bsize_max > m->bsize_max) { + if (!*get_cpu_ptr(m->scratch) || bsize_max > m->bsize_max) { + put_cpu_ptr(m->scratch); + err = pipapo_realloc_scratch(m, bsize_max); if (err) return err; @@ -1250,6 +1252,8 @@ static int nft_pipapo_insert(const struct net *net, const struct nft_set *set, this_cpu_write(nft_pipapo_scratch_index, false);

m->bsize_max = bsize_max; + } else { + put_cpu_ptr(m->scratch); }

*ext2 = &e->ext;