Messages in this thread Patch in this message | | | Date | Sun, 3 Jul 2022 22:53:31 +0900 | Subject | Re: [syzbot] KASAN: slab-out-of-bounds Write in ip6_mc_hdr | From | Taehee Yoo <> |
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Hi,
On 7/3/22 16:02, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: d521bc0a0f7c Merge branch 'mlxsw-unified-bridge-conversion.. > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=119c8ae0080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=3822ec9aaf800dfb > dashboard link: https://syzkaller.appspot.com/bug?extid=a7f5cbe0f4682a059a8e > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14c34c18080000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16fac6c0080000 > > Bisection is inconclusive: the issue happens on the oldest tested release. > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11e69790080000 > final oops: https://syzkaller.appspot.com/x/report.txt?x=13e69790080000 > console output: https://syzkaller.appspot.com/x/log.txt?x=15e69790080000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+a7f5cbe0f4682a059a8e@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: slab-out-of-bounds in ip6_flow_hdr include/net/ipv6.h:1007 [inline] > BUG: KASAN: slab-out-of-bounds in ip6_mc_hdr.constprop.0+0x4ec/0x5c0 net/ipv6/mcast.c:1715 > Write of size 4 at addr ffff888023d32fe0 by task kworker/1:3/2939 > > CPU: 1 PID: 2939 Comm: kworker/1:3 Not tainted 5.19.0-rc3-syzkaller-00644-gd521bc0a0f7c #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: mld mld_ifc_work > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313 > print_report mm/kasan/report.c:429 [inline] > kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491 > ip6_flow_hdr include/net/ipv6.h:1007 [inline] > ip6_mc_hdr.constprop.0+0x4ec/0x5c0 net/ipv6/mcast.c:1715 > mld_newpack.isra.0+0x3c0/0x770 net/ipv6/mcast.c:1763 > add_grhead+0x295/0x340 net/ipv6/mcast.c:1849 > add_grec+0x1082/0x1560 net/ipv6/mcast.c:1987 > mld_send_cr net/ipv6/mcast.c:2113 [inline] > mld_ifc_work+0x452/0xdc0 net/ipv6/mcast.c:2651 > process_one_work+0x996/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 > </TASK> > > Allocated by task 2991: > kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 > kasan_set_track mm/kasan/common.c:45 [inline] > set_alloc_info mm/kasan/common.c:436 [inline] > ____kasan_kmalloc mm/kasan/common.c:515 [inline] > ____kasan_kmalloc mm/kasan/common.c:474 [inline] > __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524 > kmalloc include/linux/slab.h:605 [inline] > kzalloc include/linux/slab.h:733 [inline] > tomoyo_encode2.part.0+0xe9/0x3a0 security/tomoyo/realpath.c:45 > tomoyo_encode2 security/tomoyo/realpath.c:31 [inline] > tomoyo_encode+0x28/0x50 security/tomoyo/realpath.c:80 > tomoyo_realpath_from_path+0x186/0x620 security/tomoyo/realpath.c:288 > tomoyo_get_realpath security/tomoyo/file.c:151 [inline] > tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822 > security_inode_getattr+0xcf/0x140 security/security.c:1344 > vfs_getattr fs/stat.c:157 [inline] > vfs_statx+0x16a/0x390 fs/stat.c:232 > vfs_fstatat+0x8c/0xb0 fs/stat.c:255 > __do_sys_newfstatat+0x91/0x110 fs/stat.c:425 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > The buggy address belongs to the object at ffff888023d32f80 > which belongs to the cache kmalloc-64 of size 64 > The buggy address is located 32 bytes to the right of > 64-byte region [ffff888023d32f80, ffff888023d32fc0) > > The buggy address belongs to the physical page: > page:ffffea00008f4c80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23d32 > flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff) > raw: 00fff00000000200 ffffea000097dec0 dead000000000003 ffff888011841640 > raw: 0000000000000000 0000000080200020 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 47, tgid 47 (kworker/u4:3), ts 9452910565, free_ts 9450274699 > prep_new_page mm/page_alloc.c:2456 [inline] > get_page_from_freelist+0x1290/0x3b70 mm/page_alloc.c:4198 > __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5426 > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272 > alloc_slab_page mm/slub.c:1824 [inline] > allocate_slab+0x26c/0x3c0 mm/slub.c:1969 > new_slab mm/slub.c:2029 [inline] > ___slab_alloc+0x9c4/0xe20 mm/slub.c:3031 > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118 > slab_alloc_node mm/slub.c:3209 [inline] > __kmalloc_node+0x2cb/0x390 mm/slub.c:4490 > kmalloc_node include/linux/slab.h:623 [inline] > __vmalloc_area_node mm/vmalloc.c:2981 [inline] > __vmalloc_node_range+0xa40/0x13e0 mm/vmalloc.c:3165 > alloc_thread_stack_node kernel/fork.c:312 [inline] > dup_task_struct kernel/fork.c:977 [inline] > copy_process+0x156e/0x7020 kernel/fork.c:2071 > kernel_clone+0xe7/0xab0 kernel/fork.c:2655 > user_mode_thread+0xad/0xe0 kernel/fork.c:2724 > call_usermodehelper_exec_work kernel/umh.c:174 [inline] > call_usermodehelper_exec_work+0xcc/0x180 kernel/umh.c:160 > process_one_work+0x996/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 > page last free stack trace: > reset_page_owner include/linux/page_owner.h:24 [inline] > free_pages_prepare mm/page_alloc.c:1371 [inline] > free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1421 > free_unref_page_prepare mm/page_alloc.c:3343 [inline] > free_unref_page+0x19/0x6a0 mm/page_alloc.c:3438 > __vunmap+0x85d/0xd30 mm/vmalloc.c:2665 > free_work+0x58/0x70 mm/vmalloc.c:97 > process_one_work+0x996/0x1610 kernel/workqueue.c:2289 > worker_thread+0x665/0x1080 kernel/workqueue.c:2436 > kthread+0x2e9/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 > > Memory state around the buggy address: > ffff888023d32e80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc > ffff888023d32f00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc >> ffff888023d32f80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc > ^ > ffff888023d33000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ffff888023d33080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this issue, for details see: > https://goo.gl/tpsmEJ#testing-patches
I think this bug is similar to(or same) https://syzkaller.appspot.com/bug?id=21bae888144b4cc906971b7651bf7511e25910a2. We can reproduce these problems with the reproducer, which the syzbot provided.
I'm suspecting this bug is from the net->ipv6.igmp_sk. When mld worker is using igmp_sk, it is possibly already freed even if it calls in6_dev_hold() before using igmp_sk.
In order to test, I add the sock_{hold | put}() to around in6_dev_{hold | put}() like follows.
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 7f695c39d9a8..4b68f46f013a 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -744,6 +744,7 @@ static void mld_add_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im) return;
pmc->idev = im->idev; + sock_hold(dev_net(idev->dev)->ipv6.igmp_sk); in6_dev_hold(idev); pmc->mca_addr = im->mca_addr; pmc->mca_crcount = idev->mc_qrv; @@ -803,6 +804,7 @@ static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im) } else { im->mca_crcount = idev->mc_qrv; } + sock_put(dev_net(pmc->idev->dev)->ipv6.igmp_sk); in6_dev_put(pmc->idev); ip6_mc_clear_src(pmc); kfree_rcu(pmc, rcu); ...
I tested again for 30 minutes, there is no problem. Anyway, I'm going to look into this more.
Thanks, Taehee Yoo
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