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Date: Sun, 2 Jun 2019 11:24:18 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Eric Dumazet <eric.dumazet@...il.com>,
Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH net-next] net: fix use-after-free in kfree_skb_list
syzbot reported nasty use-after-free [1]
Lets remove frag_list field from structs ip_fraglist_iter
and ip6_fraglist_iter. This seens not needed anyway.
[1] :
BUG: KASAN: use-after-free in kfree_skb_list+0x5d/0x60 net/core/skbuff.c:706
Read of size 8 at addr ffff888085a3cbc0 by task syz-executor303/8947
CPU: 0 PID: 8947 Comm: syz-executor303 Not tainted 5.2.0-rc2+ #12
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
__kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
kasan_report+0x12/0x20 mm/kasan/common.c:614
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
kfree_skb_list+0x5d/0x60 net/core/skbuff.c:706
ip6_fragment+0x1ef4/0x2680 net/ipv6/ip6_output.c:882
__ip6_finish_output+0x577/0xaa0 net/ipv6/ip6_output.c:144
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:156
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:179
dst_output include/net/dst.h:433 [inline]
ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1796
ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1816
rawv6_push_pending_frames net/ipv6/raw.c:617 [inline]
rawv6_sendmsg+0x2993/0x35e0 net/ipv6/raw.c:947
inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:671
___sys_sendmsg+0x803/0x920 net/socket.c:2292
__sys_sendmsg+0x105/0x1d0 net/socket.c:2330
__do_sys_sendmsg net/socket.c:2339 [inline]
__se_sys_sendmsg net/socket.c:2337 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44add9
Code: e8 7c e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 1b 05 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f826f33bce8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006e7a18 RCX: 000000000044add9
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 00000000006e7a10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e7a1c
R13: 00007ffcec4f7ebf R14: 00007f826f33c9c0 R15: 20c49ba5e353f7cf
Allocated by task 8947:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:497
slab_post_alloc_hook mm/slab.h:437 [inline]
slab_alloc_node mm/slab.c:3269 [inline]
kmem_cache_alloc_node+0x131/0x710 mm/slab.c:3579
__alloc_skb+0xd5/0x5e0 net/core/skbuff.c:199
alloc_skb include/linux/skbuff.h:1058 [inline]
__ip6_append_data.isra.0+0x2a24/0x3640 net/ipv6/ip6_output.c:1519
ip6_append_data+0x1e5/0x320 net/ipv6/ip6_output.c:1688
rawv6_sendmsg+0x1467/0x35e0 net/ipv6/raw.c:940
inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:671
___sys_sendmsg+0x803/0x920 net/socket.c:2292
__sys_sendmsg+0x105/0x1d0 net/socket.c:2330
__do_sys_sendmsg net/socket.c:2339 [inline]
__se_sys_sendmsg net/socket.c:2337 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Freed by task 8947:
save_stack+0x23/0x90 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
__cache_free mm/slab.c:3432 [inline]
kmem_cache_free+0x86/0x260 mm/slab.c:3698
kfree_skbmem net/core/skbuff.c:625 [inline]
kfree_skbmem+0xc5/0x150 net/core/skbuff.c:619
__kfree_skb net/core/skbuff.c:682 [inline]
kfree_skb net/core/skbuff.c:699 [inline]
kfree_skb+0xf0/0x390 net/core/skbuff.c:693
kfree_skb_list+0x44/0x60 net/core/skbuff.c:708
__dev_xmit_skb net/core/dev.c:3551 [inline]
__dev_queue_xmit+0x3034/0x36b0 net/core/dev.c:3850
dev_queue_xmit+0x18/0x20 net/core/dev.c:3914
neigh_direct_output+0x16/0x20 net/core/neighbour.c:1532
neigh_output include/net/neighbour.h:511 [inline]
ip6_finish_output2+0x1034/0x2550 net/ipv6/ip6_output.c:120
ip6_fragment+0x1ebb/0x2680 net/ipv6/ip6_output.c:863
__ip6_finish_output+0x577/0xaa0 net/ipv6/ip6_output.c:144
ip6_finish_output+0x38/0x1f0 net/ipv6/ip6_output.c:156
NF_HOOK_COND include/linux/netfilter.h:294 [inline]
ip6_output+0x235/0x7f0 net/ipv6/ip6_output.c:179
dst_output include/net/dst.h:433 [inline]
ip6_local_out+0xbb/0x1b0 net/ipv6/output_core.c:179
ip6_send_skb+0xbb/0x350 net/ipv6/ip6_output.c:1796
ip6_push_pending_frames+0xc8/0xf0 net/ipv6/ip6_output.c:1816
rawv6_push_pending_frames net/ipv6/raw.c:617 [inline]
rawv6_sendmsg+0x2993/0x35e0 net/ipv6/raw.c:947
inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:671
___sys_sendmsg+0x803/0x920 net/socket.c:2292
__sys_sendmsg+0x105/0x1d0 net/socket.c:2330
__do_sys_sendmsg net/socket.c:2339 [inline]
__se_sys_sendmsg net/socket.c:2337 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x49/0xbe
The buggy address belongs to the object at ffff888085a3cbc0
which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 0 bytes inside of
224-byte region [ffff888085a3cbc0, ffff888085a3cca0)
The buggy address belongs to the page:
page:ffffea0002168f00 refcount:1 mapcount:0 mapping:ffff88821b6f63c0 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00027bbf88 ffffea0002105b88 ffff88821b6f63c0
raw: 0000000000000000 ffff888085a3c080 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888085a3ca80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888085a3cb00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888085a3cb80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^
ffff888085a3cc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888085a3cc80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
Fixes: 0feca6190f88 ("net: ipv6: add skbuff fraglist splitter")
Fixes: c8b17be0b7a4 ("net: ipv4: add skbuff fraglist splitter")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/ip.h | 1 -
include/net/ipv6.h | 1 -
net/ipv4/ip_output.c | 5 ++---
net/ipv6/ip6_output.c | 5 ++---
net/ipv6/netfilter.c | 2 +-
5 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index 029cc3fd26bd7bfb1324100e068346700d0ed494..cd5cde5532d50ffd112f9ceee879e93d30fae22a 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -167,7 +167,6 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
int (*output)(struct net *, struct sock *, struct sk_buff *));
struct ip_fraglist_iter {
- struct sk_buff *frag_list;
struct sk_buff *frag;
struct iphdr *iph;
int offset;
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 21bb830e9679b19fafb245b4a7f6a1f874811bd9..0d34f6ed968140fe46574c5ce47a5e1918d44885 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -156,7 +156,6 @@ struct frag_hdr {
struct ip6_fraglist_iter {
struct ipv6hdr *tmp_hdr;
- struct sk_buff *frag_list;
struct sk_buff *frag;
int offset;
unsigned int hlen;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ceca5285d9b457b00a5d3b069a43a643c838d67d..f5636ab0b9c32fa47eaa5417fec7cdc47e4dabc2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -575,8 +575,7 @@ void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
{
unsigned int first_len = skb_pagelen(skb);
- iter->frag_list = skb_shinfo(skb)->frag_list;
- iter->frag = iter->frag_list;
+ iter->frag = skb_shinfo(skb)->frag_list;
skb_frag_list_init(skb);
iter->offset = 0;
@@ -845,7 +844,7 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
return 0;
}
- kfree_skb_list(iter.frag_list);
+ kfree_skb_list(iter.frag);
IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
return err;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 8fa83b78f81ad4b8f0e7c64583b84a228a621494..1f430cd49d8a64b7fb5ae829c7e8261a375e1053 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -613,8 +613,7 @@ int ip6_fraglist_init(struct sk_buff *skb, unsigned int hlen, u8 *prevhdr,
if (!iter->tmp_hdr)
return -ENOMEM;
- iter->frag_list = skb_shinfo(skb)->frag_list;
- iter->frag = iter->frag_list;
+ iter->frag = skb_shinfo(skb)->frag_list;
skb_frag_list_init(skb);
iter->offset = 0;
@@ -879,7 +878,7 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
return 0;
}
- kfree_skb_list(iter.frag_list);
+ kfree_skb_list(iter.frag);
IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
IPSTATS_MIB_FRAGFAILS);
diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index 9530cc2809530af59823f4f2868767338ffb39b3..d9673e10c60cc73364d3d193dbf4a04352282dc9 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -194,7 +194,7 @@ int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
if (!err)
return 0;
- kfree_skb_list(iter.frag_list);
+ kfree_skb_list(iter.frag);
return err;
}
slow_path:
--
2.22.0.rc1.257.g3120a18244-goog
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