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authorJens Axboe <axboe@kernel.dk>2019-06-21 16:20:18 (GMT)
committerJens Axboe <axboe@kernel.dk>2019-06-21 20:16:28 (GMT)
commit60c112b0ada09826cc4ae6a4e55df677f76f1313 (patch)
treefb18bb8a0819cee49f6d926d319b5e6b9f00a3ab /fs
parent440078db7a5539b36bd780a826cb6e2cf2cce0d0 (diff)
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io_uring: ensure req->file is cleared on allocation
Stephen reports: I hit the following General Protection Fault when testing io_uring via the io_uring engine in fio. This was on a VM running 5.2-rc5 and the latest version of fio. The issue occurs for both null_blk and fake NVMe drives. I have not tested bare metal or real NVMe SSDs. The fio script used is given below. [io_uring] time_based=1 runtime=60 filename=/dev/nvme2n1 (note /dev/nullb0 also fails) ioengine=io_uring bs=4k rw=readwrite direct=1 fixedbufs=1 sqthread_poll=1 sqthread_poll_cpu=0 general protection fault: 0000 [#1] SMP PTI CPU: 0 PID: 872 Comm: io_uring-sq Not tainted 5.2.0-rc5-cpacket-io-uring #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 RIP: 0010:fput_many+0x7/0x90 Code: 01 48 85 ff 74 17 55 48 89 e5 53 48 8b 1f e8 a0 f9 ff ff 48 85 db 48 89 df 75 f0 5b 5d f3 c3 0f 1f 40 00 0f 1f 44 00 00 89 f6 <f0> 48 29 77 38 74 01 c3 55 48 89 e5 53 48 89 fb 65 48 \ RSP: 0018:ffffadeb817ebc50 EFLAGS: 00010246 RAX: 0000000000000004 RBX: ffff8f46ad477480 RCX: 0000000000001805 RDX: 0000000000000000 RSI: 0000000000000001 RDI: f18b51b9a39552b5 RBP: ffffadeb817ebc58 R08: ffff8f46b7a318c0 R09: 000000000000015d R10: ffffadeb817ebce8 R11: 0000000000000020 R12: ffff8f46ad4cd000 R13: 00000000fffffff7 R14: ffffadeb817ebe30 R15: 0000000000000004 FS: 0000000000000000(0000) GS:ffff8f46b7a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055828f0bbbf0 CR3: 0000000232176004 CR4: 00000000003606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? fput+0x13/0x20 io_free_req+0x20/0x40 io_put_req+0x1b/0x20 io_submit_sqe+0x40a/0x680 ? __switch_to_asm+0x34/0x70 ? __switch_to_asm+0x40/0x70 io_submit_sqes+0xb9/0x160 ? io_submit_sqes+0xb9/0x160 ? __switch_to_asm+0x40/0x70 ? __switch_to_asm+0x34/0x70 ? __schedule+0x3f2/0x6a0 ? __switch_to_asm+0x34/0x70 io_sq_thread+0x1af/0x470 ? __switch_to_asm+0x34/0x70 ? wait_woken+0x80/0x80 ? __switch_to+0x85/0x410 ? __switch_to_asm+0x40/0x70 ? __switch_to_asm+0x34/0x70 ? __schedule+0x3f2/0x6a0 kthread+0x105/0x140 ? io_submit_sqes+0x160/0x160 ? kthread+0x105/0x140 ? io_submit_sqes+0x160/0x160 ? kthread_destroy_worker+0x50/0x50 ret_from_fork+0x35/0x40 which occurs because using a kernel side submission thread isn't valid without using fixed files (registered through io_uring_register()). This causes io_uring to put the request after logging an error, but before the file field is set in the request. If it happens to be non-zero, we attempt to fput() garbage. Fix this by ensuring that req->file is initialized when the request is allocated. Cc: stable@vger.kernel.org # 5.1+ Reported-by: Stephen Bates <sbates@raithlin.com> Tested-by: Stephen Bates <sbates@raithlin.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 86a2bd7..485832d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -579,6 +579,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
state->cur_req++;
}
+ req->file = NULL;
req->ctx = ctx;
req->flags = 0;
/* one is dropped after submission, the other at completion */
@@ -1801,10 +1802,8 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
req->sequence = ctx->cached_sq_head - 1;
}
- if (!io_op_needs_file(s->sqe)) {
- req->file = NULL;
+ if (!io_op_needs_file(s->sqe))
return 0;
- }
if (flags & IOSQE_FIXED_FILE) {
if (unlikely(!ctx->user_files ||