Date: Sun, 25 Feb 2024 21:49:37 +0800
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: syzbot <syzbot+a2e2735f09ebb9d95bd1@...kaller.appspotmail.com>,
 jgg@...pe.ca, leon@...nel.org, linux-kernel@...r.kernel.org,
 linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [rdma?] KASAN: slab-use-after-free Read in
 rdma_resolve_route



在 2024/2/24 10:12, Zhu Yanjun 写道:
> 在 2024/2/23 18:51, syzbot 写道:
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    2c3b09aac00d Add linux-next specific files for 20240214
>> git tree:       linux-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1793a064180000
>> kernel config:  
>> https://syzkaller.appspot.com/x/.config?x=176d2dcbf8ba7017
>> dashboard link: 
>> https://syzkaller.appspot.com/bug?extid=a2e2735f09ebb9d95bd1
>> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for 
>> Debian) 2.40
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> Downloadable assets:
>> disk image: 
>> https://storage.googleapis.com/syzbot-assets/ac51042b61c6/disk-2c3b09aa.raw.xz
>> vmlinux: 
>> https://storage.googleapis.com/syzbot-assets/012344301c35/vmlinux-2c3b09aa.xz
>> kernel image: 
>> https://storage.googleapis.com/syzbot-assets/cba3c3e5cd7c/bzImage-2c3b09aa.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the 
>> commit:
>> Reported-by: syzbot+a2e2735f09ebb9d95bd1@...kaller.appspotmail.com
>>
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in compare_netdev_and_ip 
>> drivers/infiniband/core/cma.c:473 [inline]
>> BUG: KASAN: slab-use-after-free in cma_add_id_to_tree 
>> drivers/infiniband/core/cma.c:513 [inline]
>> BUG: KASAN: slab-use-after-free in rdma_resolve_route+0x23f7/0x3150 
>> drivers/infiniband/core/cma.c:3379
>> Read of size 4 at addr ffff88808dcf6184 by task syz-executor.4/11929
> 
> I delved into the source code (cma.c), it seems that the spinlock 
> id_table_lock protects id_priv as below when id_priv is used:
> 
>   468 static int compare_netdev_and_ip(int ifindex_a, struct sockaddr *sa,
>   469                                  struct id_table_entry *entry_b)
>   470 {
>   471         struct rdma_id_private *id_priv = list_first_entry(
>   472                 &entry_b->id_list, struct rdma_id_private, 
> id_list_entry);
>   473         int ifindex_b = id_priv->id.route.addr.dev_addr.bound_dev_if;
>   474         struct sockaddr *sb = cma_dst_addr(id_priv);
> 
> But when id_priv is freed. No id_table_lock is used to protect id_priv 
> as below.
> 
> 2067 static void destroy_id_handler_unlock(struct rdma_id_private *id_priv)
> 2068         __releases(&idprv->handler_mutex)
> 2069 {
> 2070         enum rdma_cm_state state;
> 2071         unsigned long flags;
> 2072
> 2073         trace_cm_id_destroy(id_priv);
> 2074
> 2075         /*
> 2076          * Setting the state to destroyed under the handler mutex 
> provides a
> 2077          * fence against calling handler callbacks. If this is 
> invoked due to
> 2078          * the failure of a handler callback then it guarentees 
> that no future
> 2079          * handlers will be called.
> 2080          */
> 2081         lockdep_assert_held(&id_priv->handler_mutex);
> 2082         spin_lock_irqsave(&id_priv->lock, flags);
> 2083         state = id_priv->state;
> 2084         id_priv->state = RDMA_CM_DESTROYING;
> 2085         spin_unlock_irqrestore(&id_priv->lock, flags);
> 2086         mutex_unlock(&id_priv->handler_mutex);
> 2087         _destroy_id(id_priv, state);
> 2088 }
> 
> As such,  This causes id_priv to get out of sync.
> So a dirty and quick solution should be:
> 
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 1e2cd7c8716e..5cf034494898 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -2084,7 +2084,9 @@ static void destroy_id_handler_unlock(struct 
> rdma_id_private *id_priv)
>          id_priv->state = RDMA_CM_DESTROYING;
>          spin_unlock_irqrestore(&id_priv->lock, flags);
>          mutex_unlock(&id_priv->handler_mutex);
> +       spin_lock_irqsave(&id_table_lock, flags);
Please ignore.
id_table_lock is used in cma_remove_id_from_tree. This will cause spin 
lock embeded.

>          _destroy_id(id_priv, state);
> +       spin_unlock_irqrestore(&id_table_lock, flags);
>   }
> 
> That is, the spinlock id_table_lock is used when id_priv is freed.
> 
> And in the function compare_netdev_and_ip, when id_priv is NULL, the 
> function compare_netdev_and_ip returns directly.
> 
> RDMA stack is big and complicated. This is just my 2 cents. Please 
> comment. Thanks a lot.
> 
> Zhu Yanjun
> 
>>
>> CPU: 1 PID: 11929 Comm: syz-executor.4 Not tainted 
>> 6.8.0-rc4-next-20240214-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, 
>> BIOS Google 01/25/2024
>> Call Trace:
>>   <TASK>
>>   __dump_stack lib/dump_stack.c:88 [inline]
>>   dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>>   print_address_description mm/kasan/report.c:377 [inline]
>>   print_report+0x169/0x550 mm/kasan/report.c:488
>>   kasan_report+0x143/0x180 mm/kasan/report.c:601
>>   compare_netdev_and_ip drivers/infiniband/core/cma.c:473 [inline]
>>   cma_add_id_to_tree drivers/infiniband/core/cma.c:513 [inline]
>>   rdma_resolve_route+0x23f7/0x3150 drivers/infiniband/core/cma.c:3379
>>   ucma_resolve_route+0x1ba/0x330 drivers/infiniband/core/ucma.c:745
>>   ucma_write+0x2df/0x430 drivers/infiniband/core/ucma.c:1743
>>   vfs_write+0x2a4/0xcb0 fs/read_write.c:588
>>   ksys_write+0x1a0/0x2c0 fs/read_write.c:643
>>   do_syscall_64+0xfb/0x240
>>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
>> RIP: 0033:0x7f4eae47dda9
>> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 
>> 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 
>> 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007f4eaf2cd0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 00007f4eae5abf80 RCX: 00007f4eae47dda9
>> RDX: 0000000000000010 RSI: 0000000020000440 RDI: 0000000000000003
>> RBP: 00007f4eae4ca47a R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
>> R13: 000000000000000b R14: 00007f4eae5abf80 R15: 00007fff93bb3dc8
>>   </TASK>
>>
>> Allocated by task 11919:
>>   kasan_save_stack mm/kasan/common.c:47 [inline]
>>   kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>>   poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
>>   __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
>>   kasan_kmalloc include/linux/kasan.h:211 [inline]
>>   kmalloc_trace+0x1d9/0x360 mm/slub.c:4013
>>   kmalloc include/linux/slab.h:590 [inline]
>>   kzalloc include/linux/slab.h:711 [inline]
>>   __rdma_create_id+0x65/0x590 drivers/infiniband/core/cma.c:993
>>   rdma_create_user_id+0x83/0xc0 drivers/infiniband/core/cma.c:1049
>>   ucma_create_id+0x2d0/0x500 drivers/infiniband/core/ucma.c:463
>>   ucma_write+0x2df/0x430 drivers/infiniband/core/ucma.c:1743
>>   vfs_write+0x2a4/0xcb0 fs/read_write.c:588
>>   ksys_write+0x1a0/0x2c0 fs/read_write.c:643
>>   do_syscall_64+0xfb/0x240
>>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
>>
>> Freed by task 11915:
>>   kasan_save_stack mm/kasan/common.c:47 [inline]
>>   kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>>   kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:586
>>   poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
>>   __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
>>   kasan_slab_free include/linux/kasan.h:184 [inline]
>>   slab_free_hook mm/slub.c:2122 [inline]
>>   slab_free mm/slub.c:4296 [inline]
>>   kfree+0x14a/0x380 mm/slub.c:4406
>>   ucma_close_id drivers/infiniband/core/ucma.c:186 [inline]
>>   ucma_destroy_private_ctx+0x14e/0xc10 drivers/infiniband/core/ucma.c:578
>>   ucma_close+0xfc/0x170 drivers/infiniband/core/ucma.c:1808
>>   __fput+0x429/0x8a0 fs/file_table.c:411
>>   __do_sys_close fs/open.c:1557 [inline]
>>   __se_sys_close fs/open.c:1542 [inline]
>>   __x64_sys_close+0x7f/0x110 fs/open.c:1542
>>   do_syscall_64+0xfb/0x240
>>   entry_SYSCALL_64_after_hwframe+0x6d/0x75
>>
>> The buggy address belongs to the object at ffff88808dcf6000
>>   which belongs to the cache kmalloc-2k of size 2048
>> The buggy address is located 388 bytes inside of
>>   freed 2048-byte region [ffff88808dcf6000, ffff88808dcf6800)
>>
>> The buggy address belongs to the physical page:
>> page:ffffea0002373c00 refcount:1 mapcount:0 mapping:0000000000000000 
>> index:0x0 pfn:0x8dcf0
>> head:ffffea0002373c00 order:3 entire_mapcount:0 nr_pages_mapped:0 
>> pincount:0
>> flags: 0xfff80000000840(slab|head|node=0|zone=1|lastcpupid=0xfff)
>> page_type: 0xffffffff()
>> raw: 00fff80000000840 ffff888014c42000 dead000000000100 dead000000000122
>> raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
>> page dumped because: kasan: bad access detected
>> page_owner tracks the page as allocated
>> page last allocated via order 3, migratetype Unmovable, gfp_mask 
>> 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5149, tgid 5149 (kworker/1:4), ts 205905084555, free_ts 0
>>   set_page_owner include/linux/page_owner.h:31 [inline]
>>   post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
>>   prep_new_page mm/page_alloc.c:1540 [inline]
>>   get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
>>   __alloc_pages+0x256/0x6a0 mm/page_alloc.c:4567
>>   __alloc_pages_node include/linux/gfp.h:238 [inline]
>>   alloc_pages_node include/linux/gfp.h:261 [inline]
>>   alloc_slab_page+0x5f/0x160 mm/slub.c:2191
>>   allocate_slab mm/slub.c:2354 [inline]
>>   new_slab+0x84/0x2f0 mm/slub.c:2407
>>   ___slab_alloc+0xc73/0x1260 mm/slub.c:3541
>>   __slab_alloc mm/slub.c:3626 [inline]
>>   __slab_alloc_node mm/slub.c:3679 [inline]
>>   slab_alloc_node mm/slub.c:3851 [inline]
>>   __do_kmalloc_node mm/slub.c:3981 [inline]
>>   __kmalloc_node_track_caller+0x2d4/0x4e0 mm/slub.c:4002
>>   kmalloc_reserve+0xf3/0x260 net/core/skbuff.c:582
>>   __alloc_skb+0x1b1/0x420 net/core/skbuff.c:651
>>   alloc_skb include/linux/skbuff.h:1296 [inline]
>>   alloc_skb_with_frags+0xc3/0x780 net/core/skbuff.c:6394
>>   sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2794
>>   sock_alloc_send_skb include/net/sock.h:1855 [inline]
>>   mld_newpack+0x1c3/0xa90 net/ipv6/mcast.c:1746
>>   add_grhead net/ipv6/mcast.c:1849 [inline]
>>   add_grec+0x1492/0x19a0 net/ipv6/mcast.c:1987
>>   mld_send_cr net/ipv6/mcast.c:2113 [inline]
>>   mld_ifc_work+0x6bf/0xb30 net/ipv6/mcast.c:2650
>>   process_one_work kernel/workqueue.c:3146 [inline]
>>   process_scheduled_works+0x9d7/0x1730 kernel/workqueue.c:3226
>>   worker_thread+0x86d/0xd70 kernel/workqueue.c:3307
>> page_owner free stack trace missing
>>
>> Memory state around the buggy address:
>>   ffff88808dcf6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>   ffff88808dcf6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> ffff88808dcf6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                     ^
>>   ffff88808dcf6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>   ffff88808dcf6280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>>
>> ---
>> 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@...glegroups.com.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
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>>
>> If the report is a duplicate of another one, reply with:
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>>
>> If you want to undo deduplication, reply with:
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> 

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