In the Linux kernel, the following vulnerability has been resolved: null_blk: Always check queue mode setting from configfs Make sure to check device queue mode in the null_validate_conf() and return error for NULL_Q_RQ as we don't allow legacy I/O path, without this patch we get OOPs when queue mode is set to 1 from configfs, following are repro steps :- modprobe null_blk nr_devices=0 mkdir config/nullb/nullb0 echo 1 > config/nullb/nullb0/memory_backed echo 4096 > config/nullb/nullb0/blocksize echo 20480 > config/nullb/nullb0/size echo 1 > config/nullb/nullb0/queue_mode echo 1 > config/nullb/nullb0/power Entering kdb (current=0xffff88810acdd080, pid 2372) on processor 42 Oops: (null) due to oops @ 0xffffffffc041c329 CPU: 42 PID: 2372 Comm: sh Tainted: G O N 6.3.0-rc5lblk+ #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 RIP: 0010:null_add_dev.part.0+0xd9/0x720 [null_blk] Code: 01 00 00 85 d2 0f 85 a1 03 00 00 48 83 bb 08 01 00 00 00 0f 85 f7 03 00 00 80 bb 62 01 00 00 00 48 8b 75 20 0f 85 6d 02 00 00 <48> 89 6e 60 48 8b 75 20 bf 06 00 00 00 e8 f5 37 2c c1 48 8b 75 20 RSP: 0018:ffffc900052cbde0 EFLAGS: 00010246 RAX: 0000000000000001 RBX: ffff88811084d800 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888100042e00 RBP: ffff8881053d8200 R08: ffffc900052cbd68 R09: ffff888105db2000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000002 R13: ffff888104765200 R14: ffff88810eec1748 R15: ffff88810eec1740 FS: 00007fd445fd1740(0000) GS:ffff8897dfc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000060 CR3: 0000000166a00000 CR4: 0000000000350ee0 DR0: ffffffff8437a488 DR1: ffffffff8437a489 DR2: ffffffff8437a48a DR3: ffffffff8437a48b DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: <TASK> nullb_device_power_store+0xd1/0x120 [null_blk] configfs_write_iter+0xb4/0x120 vfs_write+0x2ba/0x3c0 ksys_write+0x5f/0xe0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc RIP: 0033:0x7fd4460c57a7 Code: 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24 RSP: 002b:00007ffd3792a4a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fd4460c57a7 RDX: 0000000000000002 RSI: 000055b43c02e4c0 RDI: 0000000000000001 RBP: 000055b43c02e4c0 R08: 000000000000000a R09: 00007fd44615b4e0 R10: 00007fd44615b3e0 R11: 0000000000000246 R12: 0000000000000002 R13: 00007fd446198520 R14: 0000000000000002 R15: 00007fd446198700 </TASK>
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