Re: [PATCH] io_uring: Fix NULL pointer dereference in loop_rw_iter()
From: Jens Axboe
Date: Wed Aug 05 2020 - 15:58:50 EST
On 8/5/20 5:02 AM, Guoyu Huang wrote:
> loop_rw_iter() does not check whether the file has a read or
> write function. This can lead to NULL pointer dereference
> when the user passes in a file descriptor that does not have
> read or write function.
>
> The crash log looks like this:
>
> [ 99.834071] BUG: kernel NULL pointer dereference, address: 0000000000000000
> [ 99.835364] #PF: supervisor instruction fetch in kernel mode
> [ 99.836522] #PF: error_code(0x0010) - not-present page
> [ 99.837771] PGD 8000000079d62067 P4D 8000000079d62067 PUD 79d8c067 PMD 0
> [ 99.839649] Oops: 0010 [#2] SMP PTI
> [ 99.840591] CPU: 1 PID: 333 Comm: io_wqe_worker-0 Tainted: G D 5.8.0 #2
> [ 99.842622] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
> [ 99.845140] RIP: 0010:0x0
> [ 99.845840] Code: Bad RIP value.
> [ 99.846672] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202
> [ 99.848018] RAX: 0000000000000000 RBX: ffff92363bd67300 RCX: ffff92363d461208
> [ 99.849854] RDX: 0000000000000010 RSI: 00007ffdbf696bb0 RDI: ffff92363bd67300
> [ 99.851743] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000
> [ 99.853394] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010
> [ 99.855148] R13: 0000000000000000 R14: ffff92363d461208 R15: ffffa1c7c01ebc68
> [ 99.856914] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000
> [ 99.858651] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 99.860032] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0
> [ 99.861979] Call Trace:
> [ 99.862617] loop_rw_iter.part.0+0xad/0x110
> [ 99.863838] io_write+0x2ae/0x380
> [ 99.864644] ? kvm_sched_clock_read+0x11/0x20
> [ 99.865595] ? sched_clock+0x9/0x10
> [ 99.866453] ? sched_clock_cpu+0x11/0xb0
> [ 99.867326] ? newidle_balance+0x1d4/0x3c0
> [ 99.868283] io_issue_sqe+0xd8f/0x1340
> [ 99.869216] ? __switch_to+0x7f/0x450
> [ 99.870280] ? __switch_to_asm+0x42/0x70
> [ 99.871254] ? __switch_to_asm+0x36/0x70
> [ 99.872133] ? lock_timer_base+0x72/0xa0
> [ 99.873155] ? switch_mm_irqs_off+0x1bf/0x420
> [ 99.874152] io_wq_submit_work+0x64/0x180
> [ 99.875192] ? kthread_use_mm+0x71/0x100
> [ 99.876132] io_worker_handle_work+0x267/0x440
> [ 99.877233] io_wqe_worker+0x297/0x350
> [ 99.878145] kthread+0x112/0x150
> [ 99.878849] ? __io_worker_unuse+0x100/0x100
> [ 99.879935] ? kthread_park+0x90/0x90
> [ 99.880874] ret_from_fork+0x22/0x30
> [ 99.881679] Modules linked in:
> [ 99.882493] CR2: 0000000000000000
> [ 99.883324] ---[ end trace 4453745f4673190b ]---
> [ 99.884289] RIP: 0010:0x0
> [ 99.884837] Code: Bad RIP value.
> [ 99.885492] RSP: 0018:ffffa1c7c01ebc08 EFLAGS: 00010202
> [ 99.886851] RAX: 0000000000000000 RBX: ffff92363acd7f00 RCX: ffff92363d461608
> [ 99.888561] RDX: 0000000000000010 RSI: 00007ffe040d9e10 RDI: ffff92363acd7f00
> [ 99.890203] RBP: ffffa1c7c01ebc40 R08: 0000000000000000 R09: 0000000000000000
> [ 99.891907] R10: ffffffff9ec692a0 R11: 0000000000000000 R12: 0000000000000010
> [ 99.894106] R13: 0000000000000000 R14: ffff92363d461608 R15: ffffa1c7c01ebc68
> [ 99.896079] FS: 0000000000000000(0000) GS:ffff92363dd00000(0000) knlGS:0000000000000000
> [ 99.898017] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 99.899197] CR2: ffffffffffffffd6 CR3: 000000007ac66000 CR4: 00000000000006e0
Thanks, applied (slightly modified for current -git), and marked with the right
fixes tag and stable CC'ed.
--
Jens Axboe