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authorEric Dumazet <edumazet@google.com>2023-09-15 19:00:35 +0000
committerDavid S. Miller <davem@davemloft.net>2023-09-18 07:10:31 +0100
commit6af289746a636f71f4c0535a9801774118486c7a (patch)
tree3b40b67cab6b12a3bfd6384e7fd4874b26376366 /net/dccp
parent3780bb29311eccb7a1c9641032a112eed237f7e3 (diff)
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dccp: fix dccp_v4_err()/dccp_v6_err() again
dh->dccph_x is the 9th byte (offset 8) in "struct dccp_hdr", not in the "byte 7" as Jann claimed. We need to make sure the ICMP messages are big enough, using more standard ways (no more assumptions). syzbot reported: BUG: KMSAN: uninit-value in pskb_may_pull_reason include/linux/skbuff.h:2667 [inline] BUG: KMSAN: uninit-value in pskb_may_pull include/linux/skbuff.h:2681 [inline] BUG: KMSAN: uninit-value in dccp_v6_err+0x426/0x1aa0 net/dccp/ipv6.c:94 pskb_may_pull_reason include/linux/skbuff.h:2667 [inline] pskb_may_pull include/linux/skbuff.h:2681 [inline] dccp_v6_err+0x426/0x1aa0 net/dccp/ipv6.c:94 icmpv6_notify+0x4c7/0x880 net/ipv6/icmp.c:867 icmpv6_rcv+0x19d5/0x30d0 ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438 ip6_input_finish net/ipv6/ip6_input.c:483 [inline] NF_HOOK include/linux/netfilter.h:304 [inline] ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492 ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586 dst_input include/net/dst.h:468 [inline] ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79 NF_HOOK include/linux/netfilter.h:304 [inline] ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310 __netif_receive_skb_one_core net/core/dev.c:5523 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5637 netif_receive_skb_internal net/core/dev.c:5723 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5782 tun_rx_batched+0x83b/0x920 tun_get_user+0x564c/0x6940 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:1985 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x15c0 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was created at: slab_post_alloc_hook+0x12f/0xb70 mm/slab.h:767 slab_alloc_node mm/slub.c:3478 [inline] kmem_cache_alloc_node+0x577/0xa80 mm/slub.c:3523 kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:559 __alloc_skb+0x318/0x740 net/core/skbuff.c:650 alloc_skb include/linux/skbuff.h:1286 [inline] alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6313 sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2795 tun_alloc_skb drivers/net/tun.c:1531 [inline] tun_get_user+0x23cf/0x6940 drivers/net/tun.c:1846 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:1985 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x15c0 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd CPU: 0 PID: 4995 Comm: syz-executor153 Not tainted 6.6.0-rc1-syzkaller-00014-ga747acc0b752 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 Fixes: 977ad86c2a1b ("dccp: Fix out of bounds access in DCCP error handler") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jann Horn <jannh@google.com> Reviewed-by: Jann Horn <jannh@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/ipv4.c9
-rw-r--r--net/dccp/ipv6.c9
2 files changed, 4 insertions, 14 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 8f56e8723c73..69453b936bd5 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -254,13 +254,8 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info)
int err;
struct net *net = dev_net(skb->dev);
- /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
- * which is in byte 7 of the dccp header.
- * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
- *
- * Later on, we want to access the sequence number fields, which are
- * beyond 8 bytes, so we have to pskb_may_pull() ourselves.
- */
+ if (!pskb_may_pull(skb, offset + sizeof(*dh)))
+ return -EINVAL;
dh = (struct dccp_hdr *)(skb->data + offset);
if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
return -EINVAL;
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 33f6ccf6ba77..c693a570682f 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -83,13 +83,8 @@ static int dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
__u64 seq;
struct net *net = dev_net(skb->dev);
- /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
- * which is in byte 7 of the dccp header.
- * Our caller (icmpv6_notify()) already pulled 8 bytes for us.
- *
- * Later on, we want to access the sequence number fields, which are
- * beyond 8 bytes, so we have to pskb_may_pull() ourselves.
- */
+ if (!pskb_may_pull(skb, offset + sizeof(*dh)))
+ return -EINVAL;
dh = (struct dccp_hdr *)(skb->data + offset);
if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
return -EINVAL;