Revision 49054556289e8787501630b7c7a9d407da02e296 authored by Paolo Abeni on 29 September 2021, 09:59:17 UTC, committed by David S. Miller on 30 September 2021, 12:06:47 UTC
Syzkaller reported a false positive deadlock involving the nl socket lock and the subflow socket lock: MPTCP: kernel_bind error, err=-98 ============================================ WARNING: possible recursive locking detected 5.15.0-rc1-syzkaller #0 Not tainted -------------------------------------------- syz-executor998/6520 is trying to acquire lock: ffff8880795718a0 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_close+0x267/0x7b0 net/mptcp/protocol.c:2738 but task is already holding lock: ffff8880787c8c60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1612 [inline] ffff8880787c8c60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_close+0x23/0x7b0 net/mptcp/protocol.c:2720 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(k-sk_lock-AF_INET); lock(k-sk_lock-AF_INET); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor998/6520: #0: ffffffff8d176c50 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802 #1: ffffffff8d176d08 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline] #1: ffffffff8d176d08 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x3e0/0x580 net/netlink/genetlink.c:790 #2: ffff8880787c8c60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1612 [inline] #2: ffff8880787c8c60 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_close+0x23/0x7b0 net/mptcp/protocol.c:2720 stack backtrace: CPU: 1 PID: 6520 Comm: syz-executor998 Not tainted 5.15.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2944 [inline] check_deadlock kernel/locking/lockdep.c:2987 [inline] validate_chain kernel/locking/lockdep.c:3776 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 lock_sock_fast+0x36/0x100 net/core/sock.c:3229 mptcp_close+0x267/0x7b0 net/mptcp/protocol.c:2738 inet_release+0x12e/0x280 net/ipv4/af_inet.c:431 __sock_release net/socket.c:649 [inline] sock_release+0x87/0x1b0 net/socket.c:677 mptcp_pm_nl_create_listen_socket+0x238/0x2c0 net/mptcp/pm_netlink.c:900 mptcp_nl_cmd_add_addr+0x359/0x930 net/mptcp/pm_netlink.c:1170 genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:731 genl_family_rcv_msg net/netlink/genetlink.c:775 [inline] genl_rcv_msg+0x328/0x580 net/netlink/genetlink.c:792 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504 genl_rcv+0x24/0x40 net/netlink/genetlink.c:803 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:724 sock_no_sendpage+0x101/0x150 net/core/sock.c:2980 kernel_sendpage.part.0+0x1a0/0x340 net/socket.c:3504 kernel_sendpage net/socket.c:3501 [inline] sock_sendpage+0xe5/0x140 net/socket.c:1003 pipe_to_sendpage+0x2ad/0x380 fs/splice.c:364 splice_from_pipe_feed fs/splice.c:418 [inline] __splice_from_pipe+0x43e/0x8a0 fs/splice.c:562 splice_from_pipe fs/splice.c:597 [inline] generic_splice_sendpage+0xd4/0x140 fs/splice.c:746 do_splice_from fs/splice.c:767 [inline] direct_splice_actor+0x110/0x180 fs/splice.c:936 splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891 do_splice_direct+0x1b3/0x280 fs/splice.c:979 do_sendfile+0xae9/0x1240 fs/read_write.c:1249 __do_sys_sendfile64 fs/read_write.c:1314 [inline] __se_sys_sendfile64 fs/read_write.c:1300 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1300 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f215cb69969 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 14 00 00 90 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc96bb3868 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f215cbad072 RCX: 00007f215cb69969 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 0000000000000000 R08: 00007ffc96bb3a08 R09: 00007ffc96bb3a08 R10: 0000000100000002 R11: 0000000000000246 R12: 00007ffc96bb387c R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000 the problem originates from uncorrect lock annotation in the mptcp code and is only visible since commit 2dcb96bacce3 ("net: core: Correct the sock::sk_lock.owned lockdep annotations"), but is present since the port-based endpoint support initial implementation. This patch addresses the issue introducing a nested variant of lock_sock_fast() and using it in the relevant code path. Fixes: 1729cf186d8a ("mptcp: create the listening socket for new port") Fixes: 2dcb96bacce3 ("net: core: Correct the sock::sk_lock.owned lockdep annotations") Suggested-by: Thomas Gleixner <tglx@linutronix.de> Reported-and-tested-by: syzbot+1dd53f7a89b299d59eaf@syzkaller.appspotmail.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>
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earlycpio.c
// SPDX-License-Identifier: GPL-2.0-only
/* ----------------------------------------------------------------------- *
*
* Copyright 2012 Intel Corporation; author H. Peter Anvin
*
* ----------------------------------------------------------------------- */
/*
* earlycpio.c
*
* Find a specific cpio member; must precede any compressed content.
* This is used to locate data items in the initramfs used by the
* kernel itself during early boot (before the main initramfs is
* decompressed.) It is the responsibility of the initramfs creator
* to ensure that these items are uncompressed at the head of the
* blob. Depending on the boot loader or package tool that may be a
* separate file or part of the same file.
*/
#include <linux/earlycpio.h>
#include <linux/kernel.h>
#include <linux/string.h>
enum cpio_fields {
C_MAGIC,
C_INO,
C_MODE,
C_UID,
C_GID,
C_NLINK,
C_MTIME,
C_FILESIZE,
C_MAJ,
C_MIN,
C_RMAJ,
C_RMIN,
C_NAMESIZE,
C_CHKSUM,
C_NFIELDS
};
/**
* find_cpio_data - Search for files in an uncompressed cpio
* @path: The directory to search for, including a slash at the end
* @data: Pointer to the cpio archive or a header inside
* @len: Remaining length of the cpio based on data pointer
* @nextoff: When a matching file is found, this is the offset from the
* beginning of the cpio to the beginning of the next file, not the
* matching file itself. It can be used to iterate through the cpio
* to find all files inside of a directory path.
*
* Return: &struct cpio_data containing the address, length and
* filename (with the directory path cut off) of the found file.
* If you search for a filename and not for files in a directory,
* pass the absolute path of the filename in the cpio and make sure
* the match returned an empty filename string.
*/
struct cpio_data find_cpio_data(const char *path, void *data,
size_t len, long *nextoff)
{
const size_t cpio_header_len = 8*C_NFIELDS - 2;
struct cpio_data cd = { NULL, 0, "" };
const char *p, *dptr, *nptr;
unsigned int ch[C_NFIELDS], *chp, v;
unsigned char c, x;
size_t mypathsize = strlen(path);
int i, j;
p = data;
while (len > cpio_header_len) {
if (!*p) {
/* All cpio headers need to be 4-byte aligned */
p += 4;
len -= 4;
continue;
}
j = 6; /* The magic field is only 6 characters */
chp = ch;
for (i = C_NFIELDS; i; i--) {
v = 0;
while (j--) {
v <<= 4;
c = *p++;
x = c - '0';
if (x < 10) {
v += x;
continue;
}
x = (c | 0x20) - 'a';
if (x < 6) {
v += x + 10;
continue;
}
goto quit; /* Invalid hexadecimal */
}
*chp++ = v;
j = 8; /* All other fields are 8 characters */
}
if ((ch[C_MAGIC] - 0x070701) > 1)
goto quit; /* Invalid magic */
len -= cpio_header_len;
dptr = PTR_ALIGN(p + ch[C_NAMESIZE], 4);
nptr = PTR_ALIGN(dptr + ch[C_FILESIZE], 4);
if (nptr > p + len || dptr < p || nptr < dptr)
goto quit; /* Buffer overrun */
if ((ch[C_MODE] & 0170000) == 0100000 &&
ch[C_NAMESIZE] >= mypathsize &&
!memcmp(p, path, mypathsize)) {
if (nextoff)
*nextoff = (long)nptr - (long)data;
if (ch[C_NAMESIZE] - mypathsize >= MAX_CPIO_FILE_NAME) {
pr_warn(
"File %s exceeding MAX_CPIO_FILE_NAME [%d]\n",
p, MAX_CPIO_FILE_NAME);
}
strlcpy(cd.name, p + mypathsize, MAX_CPIO_FILE_NAME);
cd.data = (void *)dptr;
cd.size = ch[C_FILESIZE];
return cd; /* Found it! */
}
len -= (nptr - p);
p = nptr;
}
quit:
return cd;
}
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