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Prior to access UCMA commands, the context should be initialized
and connected to CM_ID with ucma_create_id(). In case user skips
this step, he can provide non-valid ctx without CM_ID and cause
to multiple NULL dereferences.
Also there are situations where the create_id can be raced with
other user access, ensure that the context is only shared to
other threads once it is fully initialized to avoid the races.
[ 109.088108] BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
[ 109.090315] IP: ucma_connect+0x138/0x1d0
[ 109.092595] PGD 80000001dc02d067 P4D 80000001dc02d067 PUD 1da9ef067 PMD 0
[ 109.095384] Oops: 0000 [#1] SMP KASAN PTI
[ 109.097834] CPU: 0 PID: 663 Comm: uclose Tainted: G B 4.16.0-rc1-00062-g2975d5de6428 #45
[ 109.100816] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014
[ 109.105943] RIP: 0010:ucma_connect+0x138/0x1d0
[ 109.108850] RSP: 0018:ffff8801c8567a80 EFLAGS: 00010246
[ 109.111484] RAX: 0000000000000000 RBX: 1ffff100390acf50 RCX: ffffffff9d7812e2
[ 109.114496] RDX: 1ffffffff3f507a5 RSI: 0000000000000297 RDI: 0000000000000297
[ 109.117490] RBP: ffff8801daa15600 R08: 0000000000000000 R09: ffffed00390aceeb
[ 109.120429] R10: 0000000000000001 R11: ffffed00390aceea R12: 0000000000000000
[ 109.123318] R13: 0000000000000120 R14: ffff8801de6459c0 R15: 0000000000000118
[ 109.126221] FS: 00007fabb68d6700(0000) GS:ffff8801e5c00000(0000) knlGS:0000000000000000
[ 109.129468] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 109.132523] CR2: 0000000000000020 CR3: 00000001d45d8003 CR4: 00000000003606b0
[ 109.135573] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 109.138716] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 109.142057] Call Trace:
[ 109.144160] ? ucma_listen+0x110/0x110
[ 109.146386] ? wake_up_q+0x59/0x90
[ 109.148853] ? futex_wake+0x10b/0x2a0
[ 109.151297] ? save_stack+0x89/0xb0
[ 109.153489] ? _copy_from_user+0x5e/0x90
[ 109.155500] ucma_write+0x174/0x1f0
[ 109.157933] ? ucma_resolve_route+0xf0/0xf0
[ 109.160389] ? __mod_node_page_state+0x1d/0x80
[ 109.162706] __vfs_write+0xc4/0x350
[ 109.164911] ? kernel_read+0xa0/0xa0
[ 109.167121] ? path_openat+0x1b10/0x1b10
[ 109.169355] ? fsnotify+0x899/0x8f0
[ 109.171567] ? fsnotify_unmount_inodes+0x170/0x170
[ 109.174145] ? __fget+0xa8/0xf0
[ 109.177110] vfs_write+0xf7/0x280
[ 109.179532] SyS_write+0xa1/0x120
[ 109.181885] ? SyS_read+0x120/0x120
[ 109.184482] ? compat_start_thread+0x60/0x60
[ 109.187124] ? SyS_read+0x120/0x120
[ 109.189548] do_syscall_64+0xeb/0x250
[ 109.192178] entry_SYSCALL_64_after_hwframe+0x21/0x86
[ 109.194725] RIP: 0033:0x7fabb61ebe99
[ 109.197040] RSP: 002b:00007fabb68d5e98 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[ 109.200294] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fabb61ebe99
[ 109.203399] RDX: 0000000000000120 RSI: 00000000200001c0 RDI: 0000000000000004
[ 109.206548] RBP: 00007fabb68d5ec0 R08: 0000000000000000 R09: 0000000000000000
[ 109.209902] R10: 0000000000000000 R11: 0000000000000202 R12: 00007fabb68d5fc0
[ 109.213327] R13: 0000000000000000 R14: 00007fff40ab2430 R15: 00007fabb68d69c0
[ 109.216613] Code: 88 44 24 2c 0f b6 84 24 6e 01 00 00 88 44 24 2d 0f
b6 84 24 69 01 00 00 88 44 24 2e 8b 44 24 60 89 44 24 30 e8 da f6 06 ff
31 c0 <66> 41 83 7c 24 20 1b 75 04 8b 44 24 64 48 8d 74 24 20 4c 89 e7
[ 109.223602] RIP: ucma_connect+0x138/0x1d0 RSP: ffff8801c8567a80
[ 109.226256] CR2: 0000000000000020
Fixes: 7521663857 ("RDMA/cma: Export rdma cm interface to userspace")
Reported-by: <syzbot+36712f50b0552615bf59@syzkaller.appspotmail.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.