On 2018/04/12 17:03, Dmitry Vyukov wrote: > On Thu, Apr 12, 2018 at 10:01 AM, syzbot > <syzbot+0bbe42c764feafa82...@syzkaller.appspotmail.com> wrote: >> Hello, >> >> syzbot hit the following crash on https://github.com/google/kmsan.git/master >> commit >> e2ab7e8abba47a2f2698216258e5d8727ae58717 (Fri Apr 6 16:24:31 2018 +0000) >> kmsan: temporarily disable visitAsmInstruction() to help syzbot >> syzbot dashboard link: >> https://syzkaller.appspot.com/bug?extid=0bbe42c764feafa82c5a >> >> So far this crash happened 30 times on >> https://github.com/google/kmsan.git/master. >> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=4850744041668608 >> syzkaller reproducer: >> https://syzkaller.appspot.com/x/repro.syz?id=6289386287136768 >> Raw console output: >> https://syzkaller.appspot.com/x/log.txt?id=4577411249209344 >> Kernel config: >> https://syzkaller.appspot.com/x/.config?id=6627248707860932248 >> compiler: clang version 7.0.0 (trunk 329391) > > +Toshiaki as this seems to be related to the recent vlan tagging changes.
Seems not. Probably skb_vlan_tagged_multi() needs to call pskb_may_pull() before accessing skb->data? I'll confirm it later. > This also seems to be related to > https://groups.google.com/d/msg/syzkaller-bugs/FNEavkB4QaM/efXl2AeRBgAJ > > > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+0bbe42c764feafa82...@syzkaller.appspotmail.com >> It will help syzbot understand when the bug is fixed. See footer for >> details. >> If you forward the report, please keep this part and the footer. >> >> ================================================================== >> BUG: KMSAN: uninit-value in eth_type_vlan include/linux/if_vlan.h:283 >> [inline] >> BUG: KMSAN: uninit-value in skb_vlan_tagged_multi >> include/linux/if_vlan.h:656 [inline] >> BUG: KMSAN: uninit-value in vlan_features_check include/linux/if_vlan.h:672 >> [inline] >> BUG: KMSAN: uninit-value in dflt_features_check net/core/dev.c:2949 [inline] >> BUG: KMSAN: uninit-value in netif_skb_features+0xd1b/0xdc0 >> net/core/dev.c:3009 >> CPU: 1 PID: 3582 Comm: syzkaller435149 Not tainted 4.16.0+ #82 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:17 [inline] >> dump_stack+0x185/0x1d0 lib/dump_stack.c:53 >> kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 >> __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:676 >> eth_type_vlan include/linux/if_vlan.h:283 [inline] >> skb_vlan_tagged_multi include/linux/if_vlan.h:656 [inline] >> vlan_features_check include/linux/if_vlan.h:672 [inline] >> dflt_features_check net/core/dev.c:2949 [inline] >> netif_skb_features+0xd1b/0xdc0 net/core/dev.c:3009 >> validate_xmit_skb+0x89/0x1320 net/core/dev.c:3084 >> __dev_queue_xmit+0x1cb2/0x2b60 net/core/dev.c:3549 >> dev_queue_xmit+0x4b/0x60 net/core/dev.c:3590 >> packet_snd net/packet/af_packet.c:2944 [inline] >> packet_sendmsg+0x7c57/0x8a10 net/packet/af_packet.c:2969 >> sock_sendmsg_nosec net/socket.c:630 [inline] >> sock_sendmsg net/socket.c:640 [inline] >> sock_write_iter+0x3b9/0x470 net/socket.c:909 >> do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 >> do_iter_write+0x30d/0xd40 fs/read_write.c:932 >> vfs_writev fs/read_write.c:977 [inline] >> do_writev+0x3c9/0x830 fs/read_write.c:1012 >> SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 >> SyS_writev+0x56/0x80 fs/read_write.c:1082 >> do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x3d/0xa2 >> RIP: 0033:0x43ffa9 >> RSP: 002b:00007fff2cff3948 EFLAGS: 00000217 ORIG_RAX: 0000000000000014 >> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043ffa9 >> RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000003 >> RBP: 00000000006cb018 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004018d0 >> R13: 0000000000401960 R14: 0000000000000000 R15: 0000000000000000 >> >> Uninit was created at: >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] >> kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188 >> kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314 >> kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321 >> slab_post_alloc_hook mm/slab.h:445 [inline] >> slab_alloc_node mm/slub.c:2737 [inline] >> __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369 >> __kmalloc_reserve net/core/skbuff.c:138 [inline] >> __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206 >> alloc_skb include/linux/skbuff.h:984 [inline] >> alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234 >> sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2085 >> packet_alloc_skb net/packet/af_packet.c:2803 [inline] >> packet_snd net/packet/af_packet.c:2894 [inline] >> packet_sendmsg+0x6444/0x8a10 net/packet/af_packet.c:2969 >> sock_sendmsg_nosec net/socket.c:630 [inline] >> sock_sendmsg net/socket.c:640 [inline] >> sock_write_iter+0x3b9/0x470 net/socket.c:909 >> do_iter_readv_writev+0x7bb/0x970 include/linux/fs.h:1776 >> do_iter_write+0x30d/0xd40 fs/read_write.c:932 >> vfs_writev fs/read_write.c:977 [inline] >> do_writev+0x3c9/0x830 fs/read_write.c:1012 >> SYSC_writev+0x9b/0xb0 fs/read_write.c:1085 >> SyS_writev+0x56/0x80 fs/read_write.c:1082 >> do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 >> entry_SYSCALL_64_after_hwframe+0x3d/0xa2 >> ================================================================== >> >> >> --- >> This bug is generated by a dumb bot. It may contain errors. >> See https://goo.gl/tpsmEJ for details. >> Direct all questions to syzkal...@googlegroups.com. >> >> syzbot will keep track of this bug report. >> If you forgot to add the Reported-by tag, once the fix for this bug is >> merged >> into any tree, please reply to this email with: >> #syz fix: exact-commit-title >> If you want to test a patch for this bug, please reply with: >> #syz test: git://repo/address.git branch >> and provide the patch inline or as an attachment. >> To mark this as a duplicate of another syzbot report, please reply with: >> #syz dup: exact-subject-of-another-report >> If it's a one-off invalid bug report, please reply with: >> #syz invalid >> Note: if the crash happens again, it will cause creation of a new bug >> report. >> Note: all commands must start from beginning of the line in the email body. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "syzkaller-bugs" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to syzkaller-bugs+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/syzkaller-bugs/089e082d0cb81b67d10569a2283f%40google.com. >> For more options, visit https://groups.google.com/d/optout. > > -- Toshiaki Makita
