syzbot


KCSAN: data-race in lru_add_fn / tcp_build_frag

Status: fixed on 2023/02/24 13:50
Subsystems: mm
[Documentation on labels]
Fix commit: 84ce071e38a6 net: introduce __skb_fill_page_desc_noacc
First crash: 475d, last: 454d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in lru_add_fn / tcp_build_frag

write to 0xffffea00046d5d88 of 8 bytes by task 14987 on cpu 1:
 __list_add include/linux/list.h:73 [inline]
 list_add include/linux/list.h:88 [inline]
 lruvec_add_folio include/linux/mm_inline.h:105 [inline]
 lru_add_fn+0x440/0x520 mm/swap.c:228
 folio_batch_move_lru+0x1e1/0x2a0 mm/swap.c:246
 folio_batch_add_and_move mm/swap.c:263 [inline]
 folio_add_lru+0xf1/0x140 mm/swap.c:490
 filemap_add_folio+0xf8/0x150 mm/filemap.c:948
 __filemap_get_folio+0x510/0x6d0 mm/filemap.c:1981
 pagecache_get_page+0x26/0x190 mm/folio-compat.c:104
 grab_cache_page_write_begin+0x2a/0x30 mm/folio-compat.c:116
 ext4_da_write_begin+0x2dd/0x5f0 fs/ext4/inode.c:2988
 generic_perform_write+0x1d4/0x3f0 mm/filemap.c:3738
 ext4_buffered_write_iter+0x235/0x3e0 fs/ext4/file.c:270
 ext4_file_write_iter+0x2e3/0x1210
 call_write_iter include/linux/fs.h:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:578
 ksys_write+0xe8/0x1a0 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffea00046d5d88 of 8 bytes by task 15002 on cpu 0:
 page_is_pfmemalloc include/linux/mm.h:1747 [inline]
 __skb_fill_page_desc include/linux/skbuff.h:2422 [inline]
 skb_fill_page_desc include/linux/skbuff.h:2443 [inline]
 tcp_build_frag+0x613/0xb20 net/ipv4/tcp.c:1018
 do_tcp_sendpages+0x3e8/0xaf0 net/ipv4/tcp.c:1075
 tcp_sendpage_locked net/ipv4/tcp.c:1140 [inline]
 tcp_sendpage+0x89/0xb0 net/ipv4/tcp.c:1150
 inet_sendpage+0x7f/0xc0 net/ipv4/af_inet.c:833
 kernel_sendpage+0x184/0x300 net/socket.c:3561
 sock_sendpage+0x5a/0x70 net/socket.c:1054
 pipe_to_sendpage+0x128/0x160 fs/splice.c:361
 splice_from_pipe_feed fs/splice.c:415 [inline]
 __splice_from_pipe+0x222/0x4d0 fs/splice.c:559
 splice_from_pipe fs/splice.c:594 [inline]
 generic_splice_sendpage+0x89/0xc0 fs/splice.c:743
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x305/0x620 fs/splice.c:886
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64 fs/read_write.c:1303 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0xffffea0004783e48

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15002 Comm: syz-executor.0 Not tainted 6.0.0-rc4-syzkaller-00062-g0066f1b0e275-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/09/07 15:04 upstream 0066f1b0e275 c5b7bc57 .config console log report info [disk image] [vmlinux] ci2-upstream-kcsan-gce KCSAN: data-race in lru_add_fn / tcp_build_frag
2022/08/27 08:15 upstream e022620b5d05 07177916 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in lru_add_fn / tcp_build_frag
2022/08/27 08:10 upstream e022620b5d05 07177916 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in lru_add_fn / tcp_build_frag
2022/08/18 00:25 upstream 274a2eebf80c a9409d47 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in lru_add_fn / tcp_build_frag
* Struck through repros no longer work on HEAD.