Re: [PATCH net 5/5] net/sched: fix NULL dereference on the error path of tcf_skbmod_init()
Fri, Mar 16, 2018 at 12:00:57AM CET, dcara...@redhat.com wrote:
>when the following command
>
> # tc action replace action skbmod swap mac index 100
>
>is run for the first time, and tcf_skbmod_init() fails to allocate struct
>tcf_skbmod_params, tcf_skbmod_cleanup() calls kfree_rcu(NULL), thus
>causing the following error:
>
> BUG: unable to handle kernel NULL pointer dereference at 0008
> IP: __call_rcu+0x23/0x2b0
> PGD 800034057067 P4D 800034057067 PUD 74937067 PMD 0
> Oops: 0002 [#1] SMP PTI
> Modules linked in: act_skbmod(E) psample ip6table_filter ip6_tables
> iptable_filter binfmt_misc ext4 snd_hda_codec_generic snd_hda_intel
> snd_hda_codec crct10dif_pclmul mbcache jbd2 crc32_pclmul snd_hda_core
> ghash_clmulni_intel snd_hwdep pcbc snd_seq snd_seq_device snd_pcm aesni_intel
> snd_timer crypto_simd glue_helper snd cryptd virtio_balloon joydev soundcore
> pcspkr 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 drm virtio_console virtio_net virtio_blk ata_piix
> libata crc32c_intel virtio_pci serio_raw virtio_ring virtio i2c_core floppy
> dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_skbmod]
> CPU: 3 PID: 3144 Comm: tc Tainted: GE
> 4.16.0-rc4.act_vlan.orig+ #403
> Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
> RIP: 0010:__call_rcu+0x23/0x2b0
> RSP: 0018:bd2e403e7798 EFLAGS: 00010246
> RAX: c0872080 RBX: 981d34bff780 RCX:
> RDX: 922a5f00 RSI: RDI:
> RBP: R08: 0001 R09: 021f
> R10: 3d003000 R11: 00aa R12:
> R13: 922a5f00 R14: 0001 R15: 981d3b698c2c
> FS: 7f3678292740() GS:981d3fd8() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: 0008 CR3: 7c57a006 CR4: 001606e0
> Call Trace:
> __tcf_idr_release+0x79/0xf0
> tcf_skbmod_init+0x1d1/0x210 [act_skbmod]
> tcf_action_init_1+0x2cc/0x430
> 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.28+0x100/0x100
> netlink_rcv_skb+0xd2/0x110
> netlink_unicast+0x17c/0x230
> netlink_sendmsg+0x2cd/0x3c0
> sock_sendmsg+0x30/0x40
> ___sys_sendmsg+0x27a/0x290
> ? filemap_map_pages+0x34a/0x3a0
> ? __handle_mm_fault+0xbfd/0xe20
> __sys_sendmsg+0x51/0x90
> do_syscall_64+0x6e/0x1a0
> entry_SYSCALL_64_after_hwframe+0x3d/0xa2
> RIP: 0033:0x7f36776a3ba0
> RSP: 002b:7fff4703b618 EFLAGS: 0246 ORIG_RAX: 002e
> RAX: ffda RBX: 7fff4703b740 RCX: 7f36776a3ba0
> RDX: RSI: 7fff4703b690 RDI: 0003
> RBP: 5aaaba36 R08: 0002 R09:
> R10: 7fff4703b0a0 R11: 0246 R12:
> R13: 7fff4703b754 R14: 0001 R15: 00669f60
> Code: 5d e9 42 da ff ff 66 90 0f 1f 44 00 00 41 57 41 56 41 55 49 89 d5 41 54
> 55 48 89 fd 53 48 83 ec 08 40 f6 c7 07 0f 85 19 02 00 00 <48> 89 75 08 48 c7
> 45 00 00 00 00 00 9c 58 0f 1f 44 00 00 49 89
> RIP: __call_rcu+0x23/0x2b0 RSP: bd2e403e7798
> CR2: 0008
>
>Fix it in tcf_skbmod_cleanup(), ensuring that kfree_rcu(p, ...) is called
>only when p is not NULL.
>
>Fixes: 86da71b57383 ("net_sched: Introduce skbmod action")
>Signed-off-by: Davide Caratti
Acked-by: Jiri Pirko
[PATCH net 5/5] net/sched: fix NULL dereference on the error path of tcf_skbmod_init()
when the following command
# tc action replace action skbmod swap mac index 100
is run for the first time, and tcf_skbmod_init() fails to allocate struct
tcf_skbmod_params, tcf_skbmod_cleanup() calls kfree_rcu(NULL), thus
causing the following error:
BUG: unable to handle kernel NULL pointer dereference at 0008
IP: __call_rcu+0x23/0x2b0
PGD 800034057067 P4D 800034057067 PUD 74937067 PMD 0
Oops: 0002 [#1] SMP PTI
Modules linked in: act_skbmod(E) psample ip6table_filter ip6_tables
iptable_filter binfmt_misc ext4 snd_hda_codec_generic snd_hda_intel
snd_hda_codec crct10dif_pclmul mbcache jbd2 crc32_pclmul snd_hda_core
ghash_clmulni_intel snd_hwdep pcbc snd_seq snd_seq_device snd_pcm aesni_intel
snd_timer crypto_simd glue_helper snd cryptd virtio_balloon joydev soundcore
pcspkr 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 drm virtio_console virtio_net virtio_blk ata_piix
libata crc32c_intel virtio_pci serio_raw virtio_ring virtio i2c_core floppy
dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_skbmod]
CPU: 3 PID: 3144 Comm: tc Tainted: GE4.16.0-rc4.act_vlan.orig+
#403
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:__call_rcu+0x23/0x2b0
RSP: 0018:bd2e403e7798 EFLAGS: 00010246
RAX: c0872080 RBX: 981d34bff780 RCX:
RDX: 922a5f00 RSI: RDI:
RBP: R08: 0001 R09: 021f
R10: 3d003000 R11: 00aa R12:
R13: 922a5f00 R14: 0001 R15: 981d3b698c2c
FS: 7f3678292740() GS:981d3fd8() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 0008 CR3: 7c57a006 CR4: 001606e0
Call Trace:
__tcf_idr_release+0x79/0xf0
tcf_skbmod_init+0x1d1/0x210 [act_skbmod]
tcf_action_init_1+0x2cc/0x430
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.28+0x100/0x100
netlink_rcv_skb+0xd2/0x110
netlink_unicast+0x17c/0x230
netlink_sendmsg+0x2cd/0x3c0
sock_sendmsg+0x30/0x40
___sys_sendmsg+0x27a/0x290
? filemap_map_pages+0x34a/0x3a0
? __handle_mm_fault+0xbfd/0xe20
__sys_sendmsg+0x51/0x90
do_syscall_64+0x6e/0x1a0
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x7f36776a3ba0
RSP: 002b:7fff4703b618 EFLAGS: 0246 ORIG_RAX: 002e
RAX: ffda RBX: 7fff4703b740 RCX: 7f36776a3ba0
RDX: RSI: 7fff4703b690 RDI: 0003
RBP: 5aaaba36 R08: 0002 R09:
R10: 7fff4703b0a0 R11: 0246 R12:
R13: 7fff4703b754 R14: 0001 R15: 00669f60
Code: 5d e9 42 da ff ff 66 90 0f 1f 44 00 00 41 57 41 56 41 55 49 89 d5 41 54
55 48 89 fd 53 48 83 ec 08 40 f6 c7 07 0f 85 19 02 00 00 <48> 89 75 08 48 c7 45
00 00 00 00 00 9c 58 0f 1f 44 00 00 49 89
RIP: __call_rcu+0x23/0x2b0 RSP: bd2e403e7798
CR2: 0008
Fix it in tcf_skbmod_cleanup(), ensuring that kfree_rcu(p, ...) is called
only when p is not NULL.
Fixes: 86da71b57383 ("net_sched: Introduce skbmod action")
Signed-off-by: Davide Caratti
---
net/sched/act_skbmod.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
index fa975262dbac..d09565d6433e 100644
--- a/net/sched/act_skbmod.c
+++ b/net/sched/act_skbmod.c
@@ -190,7 +190,8 @@ static void tcf_skbmod_cleanup(struct tc_action *a)
struct tcf_skbmod_params *p;
p = rcu_dereference_protected(d->skbmod_p, 1);
- kfree_rcu(p, rcu);
+ if (p)
+ kfree_rcu(p, rcu);
}
static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
--
2.14.3
