From: Petar Penkov ppenkov@google.com
[ Upstream commit c39e342a050a4425348e6fe7f75827c0a1a7ebc5 ]
There is a race in the TUN driver between napi_busy_loop and napi_gro_frags. This commit resolves the race by adding the NAPI struct via netif_tx_napi_add, instead of netif_napi_add, which disables polling for the NAPI struct.
KCSAN reported: BUG: KCSAN: data-race in gro_normal_list.part.0 / napi_busy_loop
write to 0xffff8880b5d474b0 of 4 bytes by task 11205 on cpu 0: gro_normal_list.part.0+0x77/0xb0 net/core/dev.c:5682 gro_normal_list net/core/dev.c:5678 [inline] gro_normal_one net/core/dev.c:5692 [inline] napi_frags_finish net/core/dev.c:5705 [inline] napi_gro_frags+0x625/0x770 net/core/dev.c:5778 tun_get_user+0x2150/0x26a0 drivers/net/tun.c:1976 tun_chr_write_iter+0x79/0xd0 drivers/net/tun.c:2022 call_write_iter include/linux/fs.h:1895 [inline] do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693 do_iter_write fs/read_write.c:970 [inline] do_iter_write+0x13b/0x3c0 fs/read_write.c:951 vfs_writev+0x118/0x1c0 fs/read_write.c:1015 do_writev+0xe3/0x250 fs/read_write.c:1058 __do_sys_writev fs/read_write.c:1131 [inline] __se_sys_writev fs/read_write.c:1128 [inline] __x64_sys_writev+0x4e/0x60 fs/read_write.c:1128 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9
read to 0xffff8880b5d474b0 of 4 bytes by task 11168 on cpu 1: gro_normal_list net/core/dev.c:5678 [inline] napi_busy_loop+0xda/0x4f0 net/core/dev.c:6126 sk_busy_loop include/net/busy_poll.h:108 [inline] __skb_recv_udp+0x4ad/0x560 net/ipv4/udp.c:1689 udpv6_recvmsg+0x29e/0xe90 net/ipv6/udp.c:288 inet6_recvmsg+0xbb/0x240 net/ipv6/af_inet6.c:592 sock_recvmsg_nosec net/socket.c:871 [inline] sock_recvmsg net/socket.c:889 [inline] sock_recvmsg+0x92/0xb0 net/socket.c:885 sock_read_iter+0x15f/0x1e0 net/socket.c:967 call_read_iter include/linux/fs.h:1889 [inline] new_sync_read+0x389/0x4f0 fs/read_write.c:414 __vfs_read+0xb1/0xc0 fs/read_write.c:427 vfs_read fs/read_write.c:461 [inline] vfs_read+0x143/0x2c0 fs/read_write.c:446 ksys_read+0xd5/0x1b0 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x4c/0x60 fs/read_write.c:595 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 11168 Comm: syz-executor.0 Not tainted 5.4.0-rc6+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver") Signed-off-by: Petar Penkov ppenkov@google.com Reported-by: syzbot syzkaller@googlegroups.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/tun.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index e1ac1c57089f..bbd92221c6ca 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -319,8 +319,8 @@ static void tun_napi_init(struct tun_struct *tun, struct tun_file *tfile, tfile->napi_enabled = napi_en; tfile->napi_frags_enabled = napi_en && napi_frags; if (napi_en) { - netif_napi_add(tun->dev, &tfile->napi, tun_napi_poll, - NAPI_POLL_WEIGHT); + netif_tx_napi_add(tun->dev, &tfile->napi, tun_napi_poll, + NAPI_POLL_WEIGHT); napi_enable(&tfile->napi); } }