syzbot


KCSAN: data-race in lru_add_fn / skb_append_pagefrags

Status: internal: reported on 2022/10/27 01:30
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 228ebc41dfab net: do not sense pfmemalloc status in skb_append_pagefrags()
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce ci-upstream-kmsan-gce-386 ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-riscv64]
First crash: 105d, last: 105d

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

write to 0xffffea00058fc1c8 of 8 bytes by task 17319 on cpu 0:
 __list_add include/linux/list.h:73 [inline]
 list_add include/linux/list.h:88 [inline]
 lruvec_add_folio include/linux/mm_inline.h:323 [inline]
 lru_add_fn+0x327/0x410 mm/swap.c:228
 folio_batch_move_lru+0x1e1/0x2a0 mm/swap.c:246
 lru_add_drain_cpu+0x73/0x250 mm/swap.c:669
 lru_add_drain+0x21/0x60 mm/swap.c:773
 free_pages_and_swap_cache+0x16/0x70 mm/swap_state.c:311
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:256 [inline]
 tlb_flush_mmu+0x5b2/0x640 mm/mmu_gather.c:263
 tlb_finish_mmu+0x86/0x100 mm/mmu_gather.c:363
 exit_mmap+0x190/0x4d0 mm/mmap.c:3098
 __mmput+0x27/0x1b0 kernel/fork.c:1185
 mmput+0x3d/0x50 kernel/fork.c:1207
 copy_process+0x19fc/0x2100 kernel/fork.c:2518
 kernel_clone+0x166/0x550 kernel/fork.c:2671
 __do_sys_clone kernel/fork.c:2812 [inline]
 __se_sys_clone kernel/fork.c:2796 [inline]
 __x64_sys_clone+0xc3/0xf0 kernel/fork.c:2796
 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 0xffffea00058fc1c8 of 8 bytes by task 17325 on cpu 1:
 page_is_pfmemalloc include/linux/mm.h:1817 [inline]
 __skb_fill_page_desc include/linux/skbuff.h:2432 [inline]
 skb_fill_page_desc include/linux/skbuff.h:2453 [inline]
 skb_append_pagefrags+0x210/0x600 net/core/skbuff.c:3974
 unix_stream_sendpage+0x45e/0x990 net/unix/af_unix.c:2338
 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:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 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 -> 0xffffea00058fc188

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17325 Comm: syz-executor.0 Not tainted 6.1.0-rc1-syzkaller-00158-g440b7895c990-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-upstream-kcsan-gce 2022/10/22 15:50 upstream 440b7895c990 c0b80a55 .config console log report info [disk image] [vmlinux] KCSAN: data-race in lru_add_fn / skb_append_pagefrags
* Struck through repros no longer work on HEAD.