On 1/19/23 4:37?AM, Xingyuan Mo wrote: > Hello, > > Recently, when using our tool to fuzz kernel, the following bug was > triggered. > > HEAD commit: 5dc4c995db9e Linux 6.2-rc4 > git tree: mainline > compiler: gcc (Ubuntu 10.3.0-1ubuntu1~20.04) 10.3.0 > kernel config: https://drive.google.com/file/d/1anGeZxcTgSKNZX4oywvsSfLqw1tcZSTp/view?usp=share_link > C reproducer: https://drive.google.com/file/d/1DxYuWGnFSBhqve-jjXloYhwKpyUm8nDt/view?usp=share_link > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: Xingyuan Mo <hdthky0@xxxxxxxxx> > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 36200 at io_uring/io_uring.h:108 io_get_cqe_overflow root/linux-6.2-rc4/io_uring/io_uring.h:108 [inline] > WARNING: CPU: 1 PID: 36200 at io_uring/io_uring.h:108 io_get_cqe root/linux-6.2-rc4/io_uring/io_uring.h:125 [inline] > WARNING: CPU: 1 PID: 36200 at io_uring/io_uring.h:108 io_fill_cqe_aux+0x69b/0x840 root/linux-6.2-rc4/io_uring/io_uring.c:832 > Modules linked in: > CPU: 1 PID: 36200 Comm: syz-executor.0 Not tainted 6.2.0-rc4 #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 > RIP: 0010:io_get_cqe_overflow root/linux-6.2-rc4/io_uring/io_uring.h:108 [inline] > RIP: 0010:io_get_cqe root/linux-6.2-rc4/io_uring/io_uring.h:125 [inline] > RIP: 0010:io_fill_cqe_aux+0x69b/0x840 root/linux-6.2-rc4/io_uring/io_uring.c:832 > Code: fd 48 8d bb a8 00 00 00 be ff ff ff ff e8 dd 1b 02 06 31 ff 89 c5 89 c6 e8 c2 76 7e fd 85 ed 0f 85 44 fa ff ff e8 05 7a 7e fd <0f> 0b e9 38 fa ff ff e8 f9 79 7e fd 31 ff 89 ee e8 a0 76 7e fd 85 > RSP: 0018:ffffc90015747b68 EFLAGS: 00010212 > RAX: 000000000000016e RBX: ffff8881245b6000 RCX: ffffc90013881000 > RDX: 0000000000040000 RSI: ffffffff8401f31b RDI: 0000000000000005 > RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 > R13: 0000000000000000 R14: 0000000000000000 R15: ffff8881245b6018 > FS: 00007fcf02ab4700(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000001b2e024000 CR3: 00000001054e6000 CR4: 0000000000752ee0 > PKRU: 55555554 > Call Trace: > <TASK> > __io_post_aux_cqe root/linux-6.2-rc4/io_uring/io_uring.c:880 [inline] > io_post_aux_cqe+0x3b/0x90 root/linux-6.2-rc4/io_uring/io_uring.c:890 > io_msg_ring_data root/linux-6.2-rc4/io_uring/msg_ring.c:74 [inline] > io_msg_ring+0x5b9/0xb70 root/linux-6.2-rc4/io_uring/msg_ring.c:227 > io_issue_sqe+0x6c2/0x1210 root/linux-6.2-rc4/io_uring/io_uring.c:1856 > io_queue_sqe root/linux-6.2-rc4/io_uring/io_uring.c:2028 [inline] > io_submit_sqe root/linux-6.2-rc4/io_uring/io_uring.c:2286 [inline] > io_submit_sqes+0x96c/0x1e10 root/linux-6.2-rc4/io_uring/io_uring.c:2397 > __do_sys_io_uring_enter+0xc20/0x2540 root/linux-6.2-rc4/io_uring/io_uring.c:3345 > do_syscall_x64 root/linux-6.2-rc4/arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x39/0xb0 root/linux-6.2-rc4/arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7fcf01c8f6cd > Code: c3 e8 17 32 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007fcf02ab3bf8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa > RAX: ffffffffffffffda RBX: 00007fcf01dbbf80 RCX: 00007fcf01c8f6cd > RDX: 0000000000000000 RSI: 0000000000007b84 RDI: 0000000000000004 > RBP: 00007fcf01cfcb05 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007fcf01edfb2f R14: 00007fcf01edfcd0 R15: 00007fcf02ab3d80 > </TASK> I think this should fix it. Pavel? diff --git a/io_uring/msg_ring.c b/io_uring/msg_ring.c index 2d3cd945a531..c98e9c74054b 100644 --- a/io_uring/msg_ring.c +++ b/io_uring/msg_ring.c @@ -25,6 +25,28 @@ struct io_msg { u32 flags; }; +static void io_double_unlock_ctx(struct io_ring_ctx *octx) +{ + mutex_unlock(&octx->uring_lock); +} + +static int io_double_lock_ctx(struct io_ring_ctx *octx, + unsigned int issue_flags) +{ + /* + * To ensure proper ordering between the two ctxs, we can only + * attempt a trylock on the target. If that fails and we already have + * the source ctx lock, punt to io-wq. + */ + if (!(issue_flags & IO_URING_F_UNLOCKED)) { + if (!mutex_trylock(&octx->uring_lock)) + return -EAGAIN; + return 0; + } + mutex_lock(&octx->uring_lock); + return 0; +} + void io_msg_ring_cleanup(struct io_kiocb *req) { struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); @@ -43,20 +65,25 @@ static void io_msg_tw_complete(struct callback_head *head) struct io_ring_ctx *target_ctx = req->file->private_data; int ret = 0; - if (current->flags & PF_EXITING) + if (current->flags & PF_EXITING) { ret = -EOWNERDEAD; - else if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) - ret = -EOVERFLOW; + } else { + mutex_lock(&target_ctx->uring_lock); + if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) + ret = -EOVERFLOW; + mutex_unlock(&target_ctx->uring_lock); + } if (ret < 0) req_set_fail(req); io_req_queue_tw_complete(req, ret); } -static int io_msg_ring_data(struct io_kiocb *req) +static int io_msg_ring_data(struct io_kiocb *req, unsigned int issue_flags) { struct io_ring_ctx *target_ctx = req->file->private_data; struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg); + int ret; if (msg->src_fd || msg->dst_fd || msg->flags) return -EINVAL; @@ -71,33 +98,14 @@ static int io_msg_ring_data(struct io_kiocb *req) return IOU_ISSUE_SKIP_COMPLETE; } - if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) - return 0; - - return -EOVERFLOW; -} - -static void io_double_unlock_ctx(struct io_ring_ctx *octx, - unsigned int issue_flags) -{ - mutex_unlock(&octx->uring_lock); -} + if (unlikely(io_double_lock_ctx(target_ctx, issue_flags))) + return -EAGAIN; -static int io_double_lock_ctx(struct io_ring_ctx *octx, - unsigned int issue_flags) -{ - /* - * To ensure proper ordering between the two ctxs, we can only - * attempt a trylock on the target. If that fails and we already have - * the source ctx lock, punt to io-wq. - */ - if (!(issue_flags & IO_URING_F_UNLOCKED)) { - if (!mutex_trylock(&octx->uring_lock)) - return -EAGAIN; - return 0; - } - mutex_lock(&octx->uring_lock); - return 0; + ret = -EOVERFLOW; + if (io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) + ret = 0; + io_double_unlock_ctx(target_ctx); + return ret; } static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags) @@ -148,7 +156,7 @@ static int io_msg_install_complete(struct io_kiocb *req, unsigned int issue_flag if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0)) ret = -EOVERFLOW; out_unlock: - io_double_unlock_ctx(target_ctx, issue_flags); + io_double_unlock_ctx(target_ctx); return ret; } @@ -224,7 +232,7 @@ int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags) switch (msg->cmd) { case IORING_MSG_DATA: - ret = io_msg_ring_data(req); + ret = io_msg_ring_data(req, issue_flags); break; case IORING_MSG_SEND_FD: ret = io_msg_send_fd(req, issue_flags); -- Jens Axboe
