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Subject[PATCH 4.14 105/138] net/sched: fix NULL dereference in the error path of tcf_bpf_init()
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Davide Caratti <dcaratti@redhat.com>


[ Upstream commit 3239534a79ee6f20cffd974173a1e62e0730e8ac ]

when tcf_bpf_init_from_ops() fails (e.g. because of program having invalid
number of instructions), tcf_bpf_cfg_cleanup() calls bpf_prog_put(NULL) or
bpf_prog_destroy(NULL). Unless CONFIG_BPF_SYSCALL is unset, this causes
the following error:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
PGD 800000007345a067 P4D 800000007345a067 PUD 340e1067 PMD 0
Oops: 0000 [#1] SMP PTI
Modules linked in: act_bpf(E) ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 mbcache jbd2 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic pcbc snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd glue_helper cryptd joydev snd_timer snd virtio_balloon pcspkr soundcore i2c_piix4 nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm virtio_blk drm virtio_net virtio_console i2c_core crc32c_intel serio_raw virtio_pci ata_piix libata virtio_ring floppy virtio dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_bpf]
CPU: 3 PID: 5654 Comm: tc Tainted: G E 4.16.0.bpf_test+ #408
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:__bpf_prog_put+0xc/0xc0
RSP: 0018:ffff9594003ef728 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff9594003ef758 RCX: 0000000000000024
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
R10: 0000000000000220 R11: ffff8a7ab9f17131 R12: 0000000000000000
R13: ffff8a7ab7c3c8e0 R14: 0000000000000001 R15: ffff8a7ab88f1054
FS: 00007fcb2f17c740(0000) GS:ffff8a7abfd80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 000000007c888006 CR4: 00000000001606e0
Call Trace:
tcf_bpf_cfg_cleanup+0x2f/0x40 [act_bpf]
tcf_bpf_cleanup+0x4c/0x70 [act_bpf]
__tcf_idr_release+0x79/0x140
tcf_bpf_init+0x125/0x330 [act_bpf]
tcf_action_init_1+0x2cc/0x430
? get_page_from_freelist+0x3f0/0x11b0
tcf_action_init+0xd3/0x1b0
tc_ctl_action+0x18b/0x240
rtnetlink_rcv_msg+0x29c/0x310
? _cond_resched+0x15/0x30
? __kmalloc_node_track_caller+0x1b9/0x270
? rtnl_calcit.isra.29+0x100/0x100
netlink_rcv_skb+0xd2/0x110
netlink_unicast+0x17c/0x230
netlink_sendmsg+0x2cd/0x3c0
sock_sendmsg+0x30/0x40
___sys_sendmsg+0x27a/0x290
? mem_cgroup_commit_charge+0x80/0x130
? page_add_new_anon_rmap+0x73/0xc0
? do_anonymous_page+0x2a2/0x560
? __handle_mm_fault+0xc75/0xe20
__sys_sendmsg+0x58/0xa0
do_syscall_64+0x6e/0x1a0
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x7fcb2e58eba0
RSP: 002b:00007ffc93c496c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffc93c497f0 RCX: 00007fcb2e58eba0
RDX: 0000000000000000 RSI: 00007ffc93c49740 RDI: 0000000000000003
RBP: 000000005ac6a646 R08: 0000000000000002 R09: 0000000000000000
R10: 00007ffc93c49120 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc93c49804 R14: 0000000000000001 R15: 000000000066afa0
Code: 5f 00 48 8b 43 20 48 c7 c7 70 2f 7c b8 c7 40 10 00 00 00 00 5b e9 a5 8b 61 00 0f 1f 44 00 00 0f 1f 44 00 00 41 54 55 48 89 fd 53 <48> 8b 47 20 f0 ff 08 74 05 5b 5d 41 5c c3 41 89 f4 0f 1f 44 00
RIP: __bpf_prog_put+0xc/0xc0 RSP: ffff9594003ef728
CR2: 0000000000000020

Fix it in tcf_bpf_cfg_cleanup(), ensuring that bpf_prog_{put,destroy}(f)
is called only when f is not NULL.

Fixes: bbc09e7842a5 ("net/sched: fix idr leak on the error path of tcf_bpf_init()")
Reported-by: Lucas Bates <lucasb@mojatatu.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/act_bpf.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -248,10 +248,14 @@ static int tcf_bpf_init_from_efd(struct

static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg)
{
- if (cfg->is_ebpf)
- bpf_prog_put(cfg->filter);
- else
- bpf_prog_destroy(cfg->filter);
+ struct bpf_prog *filter = cfg->filter;
+
+ if (filter) {
+ if (cfg->is_ebpf)
+ bpf_prog_put(filter);
+ else
+ bpf_prog_destroy(filter);
+ }

kfree(cfg->bpf_ops);
kfree(cfg->bpf_name);

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