==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:147 [inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:1131 [inline]
BUG: KASAN: use-after-free in consume_skb+0x3c/0x250 net/core/skbuff.c:926
Read of size 4 at addr ffff88810f2519ac by task syz-executor.2/27459
CPU: 0 PID: 27459 Comm: syz-executor.2 Tainted: G W 5.15.148-syzkaller-00013-gad06eaf051cd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
print_address_description+0x87/0x3b0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:427 [inline]
kasan_report+0x179/0x1c0 mm/kasan/report.c:444
kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
__kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
refcount_read include/linux/refcount.h:147 [inline]
skb_unref include/linux/skbuff.h:1131 [inline]
consume_skb+0x3c/0x250 net/core/skbuff.c:926
__sk_msg_free+0x2dd/0x370 net/core/skmsg.c:205
sk_msg_free net/core/skmsg.c:218 [inline]
__sk_psock_purge_ingress_msg net/core/skmsg.c:768 [inline]
__sk_psock_zap_ingress net/core/skmsg.c:786 [inline]
sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:804
sock_map_close+0x2b9/0x4c0 net/core/sock_map.c:1548
unix_release+0x82/0xc0 net/unix/af_unix.c:949
__sock_release net/socket.c:649 [inline]
sock_close+0xdf/0x270 net/socket.c:1336
__fput+0x3fe/0x910 fs/file_table.c:280
____fput+0x15/0x20 fs/file_table.c:308
task_work_run+0x129/0x190 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0xc4/0xe0 kernel/entry/common.c:175
exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x26/0x160 kernel/entry/common.c:301
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f015269ed9a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 03 7f 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 63 7f 02 00 8b 44 24
RSP: 002b:00007fff6620dbd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f015269ed9a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f01527cf980 R08: 0000001b2c960000 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000293 R12: 00000000001b1eda
R13: 00000000001b1ba9 R14: 00007fff6620dd90 R15: 00007f0152656cb0
Allocated by task 27460:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:433 [inline]
__kasan_slab_alloc+0xb1/0xe0 mm/kasan/common.c:466
kasan_slab_alloc include/linux/kasan.h:217 [inline]
slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:550
slab_alloc_node mm/slub.c:3240 [inline]
slab_alloc mm/slub.c:3248 [inline]
kmem_cache_alloc+0xf5/0x200 mm/slub.c:3253
skb_clone+0x1d1/0x360 net/core/skbuff.c:1547
sk_psock_verdict_recv+0x53/0x840 net/core/skmsg.c:1182
unix_read_sock+0x132/0x370 net/unix/af_unix.c:2433
sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1225
unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1949
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2431
___sys_sendmsg+0x252/0x2e0 net/socket.c:2485
__sys_sendmsg net/socket.c:2514 [inline]
__do_sys_sendmsg net/socket.c:2523 [inline]
__se_sys_sendmsg+0x19a/0x260 net/socket.c:2521
__x64_sys_sendmsg+0x7b/0x90 net/socket.c:2521
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Freed by task 1625:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x126/0x160 mm/kasan/common.c:365
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
kasan_slab_free include/linux/kasan.h:193 [inline]
slab_free_hook mm/slub.c:1723 [inline]
slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749
slab_free mm/slub.c:3519 [inline]
kmem_cache_free+0x116/0x2e0 mm/slub.c:3535
kfree_skbmem+0x104/0x170
__kfree_skb net/core/skbuff.c:758 [inline]
kfree_skb_reason net/core/skbuff.c:778 [inline]
kfree_skb+0xc2/0x360 net/core/skbuff.c:792
sock_drop include/linux/skmsg.h:312 [inline]
sk_psock_backlog+0xc21/0xd90 net/core/skmsg.c:681
process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
kthread+0x421/0x510 kernel/kthread.c:337
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
The buggy address belongs to the object at ffff88810f2518c0
which belongs to the cache skbuff_head_cache of size 248
The buggy address is located 236 bytes inside of
248-byte region [ffff88810f2518c0, ffff88810f2519b8)
The buggy address belongs to the page:
page:ffffea00043c9440 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f251
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 0000000700000001 ffff888107f98000
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 24454, ts 1735355680182, free_ts 1706155849645
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2604
prep_new_page+0x1b/0x110 mm/page_alloc.c:2610
get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4484
__alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5776
allocate_slab mm/slub.c:1932 [inline]
new_slab+0x9a/0x4e0 mm/slub.c:1995
___slab_alloc+0x39e/0x830 mm/slub.c:3028
__slab_alloc+0x4a/0x90 mm/slub.c:3115
slab_alloc_node mm/slub.c:3206 [inline]
slab_alloc mm/slub.c:3248 [inline]
kmem_cache_alloc+0x134/0x200 mm/slub.c:3253
skb_clone+0x1d1/0x360 net/core/skbuff.c:1547
____bpf_clone_redirect net/core/filter.c:2424 [inline]
bpf_clone_redirect+0xa6/0x390 net/core/filter.c:2411
0xffffffffa03508c2
bpf_dispatcher_nop_func include/linux/bpf.h:785 [inline]
__bpf_prog_run include/linux/filter.h:625 [inline]
bpf_prog_run include/linux/filter.h:632 [inline]
bpf_test_run+0x478/0xa10 net/bpf/test_run.c:119
bpf_prog_test_run_skb+0xb41/0x1420 net/bpf/test_run.c:663
bpf_prog_test_run+0x3b0/0x630 kernel/bpf/syscall.c:3342
__sys_bpf+0x525/0x760 kernel/bpf/syscall.c:4645
__do_sys_bpf kernel/bpf/syscall.c:4731 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4729 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:4729
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1471 [inline]
free_pcp_prepare mm/page_alloc.c:1543 [inline]
free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3533
free_unref_page+0xe8/0x750 mm/page_alloc.c:3615
free_the_page mm/page_alloc.c:804 [inline]
__free_pages+0x61/0xf0 mm/page_alloc.c:5852
free_pages+0x7c/0x90 mm/page_alloc.c:5863
kasan_depopulate_vmalloc_pte+0x6a/0x90 mm/kasan/shadow.c:354
apply_to_pte_range mm/memory.c:2604 [inline]
apply_to_pmd_range mm/memory.c:2648 [inline]
apply_to_pud_range mm/memory.c:2684 [inline]
apply_to_p4d_range mm/memory.c:2720 [inline]
__apply_to_page_range+0x8dd/0xbe0 mm/memory.c:2754
apply_to_existing_page_range+0x38/0x50 mm/memory.c:2787
kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:464
__purge_vmap_area_lazy+0x154a/0x1690 mm/vmalloc.c:1715
try_purge_vmap_area_lazy+0x38/0x50 mm/vmalloc.c:1734
free_vmap_area_noflush+0x9df/0xa20 mm/vmalloc.c:1776
free_unmap_vmap_area mm/vmalloc.c:1789 [inline]
remove_vm_area+0x1d9/0x200 mm/vmalloc.c:2544
vm_remove_mappings mm/vmalloc.c:2573 [inline]
__vunmap+0x24b/0x8f0 mm/vmalloc.c:2642
__vfree mm/vmalloc.c:2700 [inline]
vfree+0x7f/0xb0 mm/vmalloc.c:2731
kvfree+0x26/0x40 mm/util.c:662
bpf_map_area_free+0x15/0x20 kernel/bpf/syscall.c:345
Memory state around the buggy address:
ffff88810f251880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
ffff88810f251900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88810f251980: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
^
ffff88810f251a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810f251a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
==================================================================
==================================================================
BUG: KASAN: double-free or invalid-free in slab_free mm/slub.c:3519 [inline]
BUG: KASAN: double-free or invalid-free in kmem_cache_free+0x116/0x2e0 mm/slub.c:3535
CPU: 0 PID: 27459 Comm: syz-executor.2 Tainted: G B W 5.15.148-syzkaller-00013-gad06eaf051cd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
print_address_description+0x87/0x3b0 mm/kasan/report.c:248
kasan_report_invalid_free+0x6b/0xa0 mm/kasan/report.c:370
____kasan_slab_free+0x13e/0x160
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
kasan_slab_free include/linux/kasan.h:193 [inline]
slab_free_hook mm/slub.c:1723 [inline]
slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749
slab_free mm/slub.c:3519 [inline]
kmem_cache_free+0x116/0x2e0 mm/slub.c:3535
kfree_skbmem+0x104/0x170
__kfree_skb net/core/skbuff.c:758 [inline]
consume_skb+0xb4/0x250 net/core/skbuff.c:930
__sk_msg_free+0x2dd/0x370 net/core/skmsg.c:205
sk_msg_free net/core/skmsg.c:218 [inline]
__sk_psock_purge_ingress_msg net/core/skmsg.c:768 [inline]
__sk_psock_zap_ingress net/core/skmsg.c:786 [inline]
sk_psock_stop+0x44c/0x4d0 net/core/skmsg.c:804
sock_map_close+0x2b9/0x4c0 net/core/sock_map.c:1548
unix_release+0x82/0xc0 net/unix/af_unix.c:949
__sock_release net/socket.c:649 [inline]
sock_close+0xdf/0x270 net/socket.c:1336
__fput+0x3fe/0x910 fs/file_table.c:280
____fput+0x15/0x20 fs/file_table.c:308
task_work_run+0x129/0x190 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0xc4/0xe0 kernel/entry/common.c:175
exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x26/0x160 kernel/entry/common.c:301
do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f015269ed9a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 03 7f 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 63 7f 02 00 8b 44 24
RSP: 002b:00007fff6620dbd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f015269ed9a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f01527cf980 R08: 0000001b2c960000 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000293 R12: 00000000001b1eda
R13: 00000000001b1ba9 R14: 00007fff6620dd90 R15: 00007f0152656cb0
Allocated by task 27460:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:433 [inline]
__kasan_slab_alloc+0xb1/0xe0 mm/kasan/common.c:466
kasan_slab_alloc include/linux/kasan.h:217 [inline]
slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:550
slab_alloc_node mm/slub.c:3240 [inline]
slab_alloc mm/slub.c:3248 [inline]
kmem_cache_alloc+0xf5/0x200 mm/slub.c:3253
skb_clone+0x1d1/0x360 net/core/skbuff.c:1547
sk_psock_verdict_recv+0x53/0x840 net/core/skmsg.c:1182
unix_read_sock+0x132/0x370 net/unix/af_unix.c:2433
sk_psock_verdict_data_ready+0x147/0x1a0 net/core/skmsg.c:1225
unix_dgram_sendmsg+0x15fa/0x2090 net/unix/af_unix.c:1949
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
____sys_sendmsg+0x59e/0x8f0 net/socket.c:2431
___sys_sendmsg+0x252/0x2e0 net/socket.c:2485
__sys_sendmsg net/socket.c:2514 [inline]
__do_sys_sendmsg net/socket.c:2523 [inline]
__se_sys_sendmsg+0x19a/0x260 net/socket.c:2521
__x64_sys_sendmsg+0x7b/0x90 net/socket.c:2521
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x61/0xcb
Freed by task 1625:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x126/0x160 mm/kasan/common.c:365
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
kasan_slab_free include/linux/kasan.h:193 [inline]
slab_free_hook mm/slub.c:1723 [inline]
slab_free_freelist_hook+0xbd/0x190 mm/slub.c:1749
slab_free mm/slub.c:3519 [inline]
kmem_cache_free+0x116/0x2e0 mm/slub.c:3535
kfree_skbmem+0x104/0x170
__kfree_skb net/core/skbuff.c:758 [inline]
kfree_skb_reason net/core/skbuff.c:778 [inline]
kfree_skb+0xc2/0x360 net/core/skbuff.c:792
sock_drop include/linux/skmsg.h:312 [inline]
sk_psock_backlog+0xc21/0xd90 net/core/skmsg.c:681
process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
kthread+0x421/0x510 kernel/kthread.c:337
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
The buggy address belongs to the object at ffff88810f2518c0
which belongs to the cache skbuff_head_cache of size 248
The buggy address is located 0 bytes inside of
248-byte region [ffff88810f2518c0, ffff88810f2519b8)
The buggy address belongs to the page:
page:ffffea00043c9440 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f251
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 0000000700000001 ffff888107f98000
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 24454, ts 1735355680182, free_ts 1706155849645
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2604
prep_new_page+0x1b/0x110 mm/page_alloc.c:2610
get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4484
__alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5776
allocate_slab mm/slub.c:1932 [inline]
new_slab+0x9a/0x4e0 mm/slub.c:1995
___slab_alloc+0x39e/0x830 mm/slub.c:3028
__slab_alloc+0x4a/0x90 mm/slub.c:3115
slab_alloc_node mm/slub.c:3206 [inline]
slab_alloc mm/slub.c:3248 [inline]
kmem_cache_alloc+0x134/0x200 mm/slub.c:3253
skb_clone+0x1d1/0x360 net/core/skbuff.c:1547
____bpf_clone_redirect net/core/filter.c:2424 [inline]
bpf_clone_redirect+0xa6/0x390 net/core/filter.c:2411
0xffffffffa03508c2
bpf_dispatcher_nop_func include/linux/bpf.h:785 [inline]
__bpf_prog_run include/linux/filter.h:625 [inline]
bpf_prog_run include/linux/filter.h:632 [inline]
bpf_test_run+0x478/0xa10 net/bpf/test_run.c:119
bpf_prog_test_run_skb+0xb41/0x1420 net/bpf/test_run.c:663
bpf_prog_test_run+0x3b0/0x630 kernel/bpf/syscall.c:3342
__sys_bpf+0x525/0x760 kernel/bpf/syscall.c:4645
__do_sys_bpf kernel/bpf/syscall.c:4731 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4729 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:4729
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1471 [inline]
free_pcp_prepare mm/page_alloc.c:1543 [inline]
free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3533
free_unref_page+0xe8/0x750 mm/page_alloc.c:3615
free_the_page mm/page_alloc.c:804 [inline]
__free_pages+0x61/0xf0 mm/page_alloc.c:5852
free_pages+0x7c/0x90 mm/page_alloc.c:5863
kasan_depopulate_vmalloc_pte+0x6a/0x90 mm/kasan/shadow.c:354
apply_to_pte_range mm/memory.c:2604 [inline]
apply_to_pmd_range mm/memory.c:2648 [inline]
apply_to_pud_range mm/memory.c:2684 [inline]
apply_to_p4d_range mm/memory.c:2720 [inline]
__apply_to_page_range+0x8dd/0xbe0 mm/memory.c:2754
apply_to_existing_page_range+0x38/0x50 mm/memory.c:2787
kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:464
__purge_vmap_area_lazy+0x154a/0x1690 mm/vmalloc.c:1715
try_purge_vmap_area_lazy+0x38/0x50 mm/vmalloc.c:1734
free_vmap_area_noflush+0x9df/0xa20 mm/vmalloc.c:1776
free_unmap_vmap_area mm/vmalloc.c:1789 [inline]
remove_vm_area+0x1d9/0x200 mm/vmalloc.c:2544
vm_remove_mappings mm/vmalloc.c:2573 [inline]
__vunmap+0x24b/0x8f0 mm/vmalloc.c:2642
__vfree mm/vmalloc.c:2700 [inline]
vfree+0x7f/0xb0 mm/vmalloc.c:2731
kvfree+0x26/0x40 mm/util.c:662
bpf_map_area_free+0x15/0x20 kernel/bpf/syscall.c:345
Memory state around the buggy address:
ffff88810f251780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88810f251800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
>ffff88810f251880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff88810f251900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88810f251980: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
==================================================================