io_uring: fix null-ptr-deref in io_sq_offload_start()
I met a null-ptr-deref when doing fault-inject test:
[ 65.441626][ T8299] general protection fault, probably for non-canonical address 0xdffffc0000000029: 0000 [#1] PREEMPT SMP KASAN
[ 65.443219][ T8299] KASAN: null-ptr-deref in range [0x0000000000000148-0x000000000000014f]
[ 65.444331][ T8299] CPU: 2 PID: 8299 Comm: test Not tainted 5.10.49+ #499
[ 65.445277][ T8299] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 65.446614][ T8299] RIP: 0010:io_disable_sqo_submit+0x124/0x260
[ 65.447554][ T8299] Code: 7b 40 89 ee e8 2d b9 9a ff 85 ed 74 40 e8 04 b8 9a ff 49 8d be 48 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 22 01 00 00 49 8b ae 48 01 00 00 48 85 ed 74 0d
[ 65.450860][ T8299] RSP: 0018:
ffffc9000122fd70 EFLAGS:
00010202
[ 65.451826][ T8299] RAX:
dffffc0000000000 RBX:
ffff88801b11f000 RCX:
ffffffff81d5d783
[ 65.453166][ T8299] RDX:
0000000000000029 RSI:
ffffffff81d5d78c RDI:
0000000000000148
[ 65.454606][ T8299] RBP:
0000000000000002 R08:
ffff88810168c280 R09:
ffffed1003623e79
[ 65.456063][ T8299] R10:
ffffc9000122fd70 R11:
ffffed1003623e78 R12:
ffff88801b11f040
[ 65.457542][ T8299] R13:
ffff88801b11f3c0 R14:
0000000000000000 R15:
000000000000001a
[ 65.458910][ T8299] FS:
00007ffb602e3500(0000) GS:
ffff888064100000(0000) knlGS:
0000000000000000
[ 65.460533][ T8299] CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
[ 65.461736][ T8299] CR2:
00007ffb5fe7eb24 CR3:
000000010a619000 CR4:
0000000000750ee0
[ 65.463146][ T8299] DR0:
0000000000000000 DR1:
0000000000000000 DR2:
0000000000000000
[ 65.464618][ T8299] DR3:
0000000000000000 DR6:
00000000fffe0ff0 DR7:
0000000000000400
[ 65.466052][ T8299] PKRU:
55555554
[ 65.466708][ T8299] Call Trace:
[ 65.467304][ T8299] io_uring_setup+0x2041/0x3ac0
[ 65.468169][ T8299] ? io_iopoll_check+0x500/0x500
[ 65.469123][ T8299] ? syscall_enter_from_user_mode+0x1c/0x50
[ 65.470241][ T8299] do_syscall_64+0x2d/0x70
[ 65.471028][ T8299] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 65.472099][ T8299] RIP: 0033:0x7ffb5fdec839
[ 65.472925][ T8299] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48
[ 65.476465][ T8299] RSP: 002b:
00007ffc33539ef8 EFLAGS:
00000206 ORIG_RAX:
00000000000001a9
[ 65.478026][ T8299] RAX:
ffffffffffffffda RBX:
0000000000000000 RCX:
00007ffb5fdec839
[ 65.479503][ T8299] RDX:
0000000020ffd000 RSI:
0000000020000080 RDI:
0000000000100001
[ 65.480927][ T8299] RBP:
00007ffc33539f70 R08:
0000000000000000 R09:
0000000000000000
[ 65.482416][ T8299] R10:
0000000000000000 R11:
0000000000000206 R12:
0000555e85531320
[ 65.483845][ T8299] R13:
00007ffc3353a0a0 R14:
0000000000000000 R15:
0000000000000000
[ 65.485331][ T8299] Modules linked in:
[ 65.486000][ T8299] Dumping ftrace buffer:
[ 65.486772][ T8299] (ftrace buffer empty)
[ 65.487595][ T8299] ---[ end trace
a9a5fad3ebb303b7 ]---
If io_allocate_scq_urings() fails in io_uring_create(), 'ctx->sq_data'
is not set yet, when calling io_sq_offload_start() in io_disable_sqo_submit()
in error path, it will lead a null-ptr-deref.
The io_disable_sqo_submit() has been removed in mainline by commit
70aacfe66136 ("io_uring: kill sqo_dead and sqo submission halting"),
so the bug has been eliminated in mainline, it's a fix only for stable-5.10.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>