Re: [PATCH bpf 1/3] bpf: tcp_read_skb needs to pop skb regardless of seq

kernel test robot
2023-09-23T14:38:09Z

Hi John,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf/master]

url: https://github.com/intel-lab-lkp/linux/commits/John-Fastabend/bpf-tcp_read_skb-needs-to-pop-skb-regardless-of-seq/20230921-073209
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
patch link: https://lore.kernel.org/r/20230920232706.498747-2-john.fastabend%40gmail.com
patch subject: [PATCH bpf 1/3] bpf: tcp_read_skb needs to pop skb regardless of seq
config: um-allnoconfig (https://download.01.org/0day-ci/archive/20230923/202309232236.36lvZlKR-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230923/202309232236.36lvZlKR-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309232236.36lvZlKR-lkp@intel.com/

All warnings (new ones prefixed by >>):

In file included from net/ipv4/tcp.c:252:
In file included from include/linux/inet_diag.h:5:
In file included from include/net/netlink.h:6:
In file included from include/linux/netlink.h:7:
In file included from include/linux/skbuff.h:17:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:5:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
547 | val = __raw_readb(PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
560 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
| ^
In file included from net/ipv4/tcp.c:252:
In file included from include/linux/inet_diag.h:5:
In file included from include/net/netlink.h:6:
In file included from include/linux/netlink.h:7:
In file included from include/linux/skbuff.h:17:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:5:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
573 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
In file included from net/ipv4/tcp.c:252:
In file included from include/linux/inet_diag.h:5:
In file included from include/net/netlink.h:6:
In file included from include/linux/netlink.h:7:
In file included from include/linux/skbuff.h:17:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:5:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
584 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
594 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
604 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:692:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
692 | readsb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:700:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
700 | readsw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:708:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
708 | readsl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:717:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
717 | writesb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:726:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
726 | writesw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:735:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
735 | writesl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
>> net/ipv4/tcp.c:1625:6: warning: variable 'seq' set but not used [-Wunused-but-set-variable]
1625 | u32 seq = tp->copied_seq;
| ^
13 warnings generated.

vim +/seq +1625 net/ipv4/tcp.c

^1da177e4c3f41 Linus Torvalds 2005-04-16 1621
965b57b469a589 Cong Wang 2022-06-15 1622 int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
04919bed948dc2 Cong Wang 2022-06-15 1623 {
04919bed948dc2 Cong Wang 2022-06-15 1624 struct tcp_sock *tp = tcp_sk(sk);
04919bed948dc2 Cong Wang 2022-06-15 @1625 u32 seq = tp->copied_seq;
04919bed948dc2 Cong Wang 2022-06-15 1626 struct sk_buff *skb;
04919bed948dc2 Cong Wang 2022-06-15 1627 int copied = 0;
04919bed948dc2 Cong Wang 2022-06-15 1628
04919bed948dc2 Cong Wang 2022-06-15 1629 if (sk->sk_state == TCP_LISTEN)
04919bed948dc2 Cong Wang 2022-06-15 1630 return -ENOTCONN;
04919bed948dc2 Cong Wang 2022-06-15 1631
98edede7d6d1b6 John Fastabend 2023-09-20 1632 while ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) {
db4192a754ebd5 Cong Wang 2022-09-12 1633 u8 tcp_flags;
db4192a754ebd5 Cong Wang 2022-09-12 1634 int used;
04919bed948dc2 Cong Wang 2022-06-15 1635
04919bed948dc2 Cong Wang 2022-06-15 1636 __skb_unlink(skb, &sk->sk_receive_queue);
96628951869c0d Peilin Ye 2022-09-08 1637 WARN_ON_ONCE(!skb_set_owner_sk_safe(skb, sk));
db4192a754ebd5 Cong Wang 2022-09-12 1638 tcp_flags = TCP_SKB_CB(skb)->tcp_flags;
db4192a754ebd5 Cong Wang 2022-09-12 1639 used = recv_actor(sk, skb);
db4192a754ebd5 Cong Wang 2022-09-12 1640 if (used < 0) {
db4192a754ebd5 Cong Wang 2022-09-12 1641 if (!copied)
db4192a754ebd5 Cong Wang 2022-09-12 1642 copied = used;
db4192a754ebd5 Cong Wang 2022-09-12 1643 break;
db4192a754ebd5 Cong Wang 2022-09-12 1644 }
db4192a754ebd5 Cong Wang 2022-09-12 1645 seq += used;
db4192a754ebd5 Cong Wang 2022-09-12 1646 copied += used;
db4192a754ebd5 Cong Wang 2022-09-12 1647
db4192a754ebd5 Cong Wang 2022-09-12 1648 if (tcp_flags & TCPHDR_FIN) {
04919bed948dc2 Cong Wang 2022-06-15 1649 ++seq;
db4192a754ebd5 Cong Wang 2022-09-12 1650 break;
db4192a754ebd5 Cong Wang 2022-09-12 1651 }
04919bed948dc2 Cong Wang 2022-06-15 1652 }
04919bed948dc2 Cong Wang 2022-06-15 1653 return copied;
04919bed948dc2 Cong Wang 2022-06-15 1654 }
04919bed948dc2 Cong Wang 2022-06-15 1655 EXPORT_SYMBOL(tcp_read_skb);
04919bed948dc2 Cong Wang 2022-06-15 1656

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