Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754165AbeANHYA (ORCPT + 1 other); Sun, 14 Jan 2018 02:24:00 -0500 Received: from mail-pl0-f65.google.com ([209.85.160.65]:42646 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751864AbeANHX6 (ORCPT ); Sun, 14 Jan 2018 02:23:58 -0500 X-Google-Smtp-Source: ACJfBosdc0muu6VpMfLDmbfR36/CRwtaAgbmEmvJRKdjANOjXAVkrLtr0tfBlZv/2QnUG63R+NIWmzSVBy+GMBGKevE= MIME-Version: 1.0 In-Reply-To: <461fe119-d452-6270-7126-46dd208a2767@iogearbox.net> References: <001a11445a8803c8c705629eb602@google.com> <461fe119-d452-6270-7126-46dd208a2767@iogearbox.net> From: Dmitry Vyukov Date: Sun, 14 Jan 2018 08:23:37 +0100 Message-ID: Subject: Re: KASAN: slab-out-of-bounds Read in map_lookup_elem To: Daniel Borkmann Cc: syzbot , Alexei Starovoitov , LKML , netdev , syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Sun, Jan 14, 2018 at 1:13 AM, Daniel Borkmann wrote: > On 01/13/2018 02:58 AM, syzbot wrote: >> Hello, >> >> syzkaller hit the following crash on 19d28fbd306e7ae7c1acf05c3e6968b56f0d196b >> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master >> compiler: gcc (GCC) 7.1.1 20170620 >> .config is attached >> Raw console output is attached. >> C reproducer is attached >> syzkaller reproducer is attached. See https://goo.gl/kgGztJ >> for information about syzkaller reproducers > > Fixed here as well: > > https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=bbeb6e4323dad9b5e0ee9f60c223dd532e2403b1 Thanks. Let's tell syzbot about this so that it reports bugs in map_lookup_elem ever again: #syz fix: bpf, array: fix overflow in max_entries and undefined behavior in index_mask >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+e631b5eb810eae08510d@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. >> >> audit: type=1400 audit(1515782899.456:8): avc: denied { sys_admin } for pid=3501 comm="syzkaller937663" capability=21 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 >> audit: type=1400 audit(1515782899.512:9): avc: denied { sys_chroot } for pid=3502 comm="syzkaller937663" capability=18 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1 >> ================================================================== >> BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:344 [inline] >> BUG: KASAN: slab-out-of-bounds in map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584 >> Read of size 2097153 at addr ffff8801bfc7e690 by task syzkaller937663/3502 >> >> CPU: 0 PID: 3502 Comm: syzkaller937663 Not tainted 4.15.0-rc7+ #185 >> 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+0x194/0x257 lib/dump_stack.c:53 >> print_address_description+0x73/0x250 mm/kasan/report.c:252 >> kasan_report_error mm/kasan/report.c:351 [inline] >> kasan_report+0x25b/0x340 mm/kasan/report.c:409 >> check_memory_region_inline mm/kasan/kasan.c:260 [inline] >> check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 >> memcpy+0x23/0x50 mm/kasan/kasan.c:302 >> memcpy include/linux/string.h:344 [inline] >> map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584 >> SYSC_bpf kernel/bpf/syscall.c:1808 [inline] >> SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1782 >> entry_SYSCALL_64_fastpath+0x23/0x9a >> RIP: 0033:0x440ab9 >> RSP: 002b:00000000007dff68 EFLAGS: 00000203 ORIG_RAX: 0000000000000141 >> RAX: ffffffffffffffda RBX: 00007fffc494ea60 RCX: 0000000000440ab9 >> RDX: 0000000000000018 RSI: 0000000020eab000 RDI: 0000000000000001 >> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000000 R11: 0000000000000203 R12: 0000000000402290 >> R13: 0000000000402320 R14: 0000000000000000 R15: 0000000000000000 >> >> Allocated by task 3502: >> save_stack+0x43/0xd0 mm/kasan/kasan.c:447 >> set_track mm/kasan/kasan.c:459 [inline] >> kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 >> __do_kmalloc_node mm/slab.c:3672 [inline] >> __kmalloc_node+0x47/0x70 mm/slab.c:3679 >> kmalloc_node include/linux/slab.h:541 [inline] >> bpf_map_area_alloc+0x32/0x80 kernel/bpf/syscall.c:123 >> array_map_alloc+0x351/0xa00 kernel/bpf/arraymap.c:96 >> find_and_alloc_map kernel/bpf/syscall.c:105 [inline] >> map_create kernel/bpf/syscall.c:404 [inline] >> SYSC_bpf kernel/bpf/syscall.c:1805 [inline] >> SyS_bpf+0x7f8/0x4400 kernel/bpf/syscall.c:1782 >> entry_SYSCALL_64_fastpath+0x23/0x9a >> >> Freed by task 1966: >> save_stack+0x43/0xd0 mm/kasan/kasan.c:447 >> set_track mm/kasan/kasan.c:459 [inline] >> kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524 >> __cache_free mm/slab.c:3488 [inline] >> kfree+0xd6/0x260 mm/slab.c:3803 >> seq_release fs/seq_file.c:366 [inline] >> single_release+0x80/0xb0 fs/seq_file.c:602 >> __fput+0x327/0x7e0 fs/file_table.c:210 >> ____fput+0x15/0x20 fs/file_table.c:244 >> task_work_run+0x199/0x270 kernel/task_work.c:113 >> tracehook_notify_resume include/linux/tracehook.h:191 [inline] >> exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162 >> prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] >> syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264 >> entry_SYSCALL_64_fastpath+0x98/0x9a >> >> The buggy address belongs to the object at ffff8801bfc7e5c0 >> which belongs to the cache kmalloc-256 of size 256 >> The buggy address is located 208 bytes inside of >> 256-byte region [ffff8801bfc7e5c0, ffff8801bfc7e6c0) >> The buggy address belongs to the page: >> page:ffffea0006ff1f80 count:1 mapcount:0 mapping:ffff8801bfc7e0c0 index:0x0 >> flags: 0x2fffc0000000100(slab) >> raw: 02fffc0000000100 ffff8801bfc7e0c0 0000000000000000 000000010000000c >> raw: ffffea00070149e0 ffffea0006ff2be0 ffff8801dac007c0 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff8801bfc7e580: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 >> ffff8801bfc7e600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >>> ffff8801bfc7e680: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc >> ^ >> ffff8801bfc7e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff8801bfc7e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ================================================================== >> >> >> --- >> This bug is generated by a dumb bot. It may contain errors. >> See https://goo.gl/tpsmEJ for details. >> Direct all questions to syzkaller@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+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/461fe119-d452-6270-7126-46dd208a2767%40iogearbox.net. > For more options, visit https://groups.google.com/d/optout.