================================================================== BUG: KASAN: use-after-free in skb_frag_size include/linux/skbuff.h:330 [inline] BUG: KASAN: use-after-free in __skb_datagram_iter+0x6b8/0x770 net/core/datagram.c:441 Read of size 4 at addr ffff888028708004 by task syz-fuzzer/8423 CPU: 0 PID: 8423 Comm: syz-fuzzer Not tainted 5.12.0-rc8-next-20210423-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436 skb_frag_size include/linux/skbuff.h:330 [inline] __skb_datagram_iter+0x6b8/0x770 net/core/datagram.c:441 skb_copy_datagram_iter+0x40/0x50 net/core/datagram.c:533 skb_copy_datagram_msg include/linux/skbuff.h:3602 [inline] tcp_recvmsg_locked+0x1048/0x22f0 net/ipv4/tcp.c:2472 tcp_recvmsg+0x134/0x550 net/ipv4/tcp.c:2550 inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:852 sock_recvmsg_nosec net/socket.c:888 [inline] sock_recvmsg net/socket.c:906 [inline] sock_recvmsg net/socket.c:902 [inline] sock_read_iter+0x33c/0x470 net/socket.c:979 call_read_iter include/linux/fs.h:2108 [inline] new_sync_read+0x5b7/0x6e0 fs/read_write.c:415 vfs_read+0x35c/0x570 fs/read_write.c:496 ksys_read+0x1ee/0x250 fs/read_write.c:634 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4af19b Code: fb ff eb bd e8 a6 b6 fb ff e9 61 ff ff ff cc e8 9b 82 fb ff 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 28 ff ff ff ff 48 c7 44 24 30 RSP: 002b:000000c0003a7828 EFLAGS: 00000212 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000000c00001c000 RCX: 00000000004af19b RDX: 0000000000001000 RSI: 000000c000072000 RDI: 0000000000000006 RBP: 000000c0003a7878 R08: 0000000000000001 R09: 0000000000000002 R10: 0000000000002365 R11: 0000000000000212 R12: 0000000000002361 R13: 0000000000000200 R14: 0000000000000020 R15: 0000000000000004 Allocated by task 1: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:428 [inline] __kasan_slab_alloc+0x84/0xa0 mm/kasan/common.c:461 kasan_slab_alloc include/linux/kasan.h:236 [inline] slab_post_alloc_hook mm/slab.h:527 [inline] slab_alloc_node mm/slub.c:2924 [inline] slab_alloc mm/slub.c:2932 [inline] kmem_cache_alloc+0x219/0x3a0 mm/slub.c:2937 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags include/linux/audit.h:319 [inline] getname+0x8e/0xd0 fs/namei.c:209 do_sys_openat2+0xf5/0x420 fs/open.c:1181 do_sys_open fs/open.c:1203 [inline] __do_sys_open fs/open.c:1211 [inline] __se_sys_open fs/open.c:1207 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1207 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 12366: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357 ____kasan_slab_free mm/kasan/common.c:360 [inline] ____kasan_slab_free mm/kasan/common.c:325 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:368 kasan_slab_free include/linux/kasan.h:212 [inline] slab_free_hook mm/slub.c:1593 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1618 slab_free mm/slub.c:3178 [inline] kmem_cache_free+0x97/0x750 mm/slub.c:3194 putname+0xe1/0x120 fs/namei.c:259 do_sys_openat2+0x153/0x420 fs/open.c:1196 do_sys_open fs/open.c:1203 [inline] __do_sys_open fs/open.c:1211 [inline] __se_sys_open fs/open.c:1207 [inline] __x64_sys_open+0x119/0x1c0 fs/open.c:1207 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff888028708000 which belongs to the cache names_cache of size 4096 The buggy address is located 4 bytes inside of 4096-byte region [ffff888028708000, ffff888028709000) The buggy address belongs to the page: page:ffffea0000a1c200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28708 head:ffffea0000a1c200 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 dead000000000100 dead000000000122 ffff8880111be280 raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888028707f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888028707f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888028708000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888028708080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888028708100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================