kernel/linux.git/io_uring/kbuf.c, branch v6.6.132

io_uring/kbuf: check if target buffer list is still legacy on recycle

2026-03-25T10:06:02+00:00

Commit c2c185be5c85d37215397c8e8781abf0a69bec1f upstream. There's a gap between when the buffer was grabbed and when it potentially gets recycled, where if the list is empty, someone could've upgraded it to a ring provided type. This can happen if the request is forced via io-wq. The legacy recycling is missing checking if the buffer_list still exists, and if it's of the correct type. Add those checks. Cc: stable@vger.kernel.org Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Reported-by: Keenan Dong Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/kbuf: account ring io_buffer_list memory

2025-06-27T10:08:43+00:00

commit 475a8d30371604a6363da8e304a608a5959afc40 upstream. Follow the non-ringed pbuf struct io_buffer_list allocations and account it against the memcg. There is low chance of that being an actual problem as ring provided buffer should either pin user memory or allocate it, which is already accounted. Cc: stable@vger.kernel.org # 6.1 Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/3985218b50d341273cafff7234e1a7e6d0db9808.1747150490.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: add io_file_can_poll() helper

2025-06-19T13:28:44+00:00

Commit 95041b93e90a06bb613ec4bef9cd4d61570f68e4 upstream. This adds a flag to avoid dipping dereferencing file and then f_op to figure out if the file has a poll handler defined or not. We generally call this at least twice for networked workloads, and if using ring provided buffers, we do it on every buffer selection. Particularly the latter is troublesome, as it's otherwise a very fast operation. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/kbuf: reject zero sized provided buffers

2025-04-25T08:45:26+00:00

commit cf960726eb65e8d0bfecbcce6cf95f47b1ffa6cc upstream. This isn't fixing a real issue, but there's also zero point in going through group and buffer setup, when the buffers are going to be rejected once attempted to get used. Cc: stable@vger.kernel.org Reported-by: syzbot+58928048fd1416f1457c@syzkaller.appspotmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: fix error pbuf checking

2025-03-22T19:50:45+00:00

Commit bcc87d978b834c298bbdd9c52454c5d0a946e97e upstream. Syz reports a problem, which boils down to NULL vs IS_ERR inconsistent error handling in io_alloc_pbuf_ring(). KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:__io_remove_buffers+0xac/0x700 io_uring/kbuf.c:341 Call Trace: io_put_bl io_uring/kbuf.c:378 [inline] io_destroy_buffers+0x14e/0x490 io_uring/kbuf.c:392 io_ring_ctx_free+0xa00/0x1070 io_uring/io_uring.c:2613 io_ring_exit_work+0x80f/0x8a0 io_uring/io_uring.c:2844 process_one_work kernel/workqueue.c:3231 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312 worker_thread+0x86d/0xd40 kernel/workqueue.c:3390 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Cc: stable@vger.kernel.org Reported-by: syzbot+2074b1a3d447915c6f1c@syzkaller.appspotmail.com Fixes: 87585b05757dc ("io_uring/kbuf: use vm_insert_pages() for mmap'ed pbuf ring") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/c5f9df20560bd9830401e8e48abc029e7cfd9f5e.1721329239.git.asml.silence@gmail.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: use unpin_user_pages() where appropriate

2025-03-22T19:50:45+00:00

Commit 18595c0a58ae29ac6a996c5b664610119b73182d upstream. There are a few cases of open-rolled loops around unpin_user_page(), use the generic helper instead. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/kbuf: use vm_insert_pages() for mmap'ed pbuf ring

2025-03-22T19:50:45+00:00

Commit 87585b05757dc70545efb434669708d276125559 upstream. Rather than use remap_pfn_range() for this and manually free later, switch to using vm_insert_page() and have it Just Work. This requires a bit of effort on the mmap lookup side, as the ctx uring_lock isn't held, which otherwise protects buffer_lists from being torn down, and it's not safe to grab from mmap context that would introduce an ABBA deadlock between the mmap lock and the ctx uring_lock. Instead, lookup the buffer_list under RCU, as the the list is RCU freed already. Use the existing reference count to determine whether it's possible to safely grab a reference to it (eg if it's not zero already), and drop that reference when done with the mapping. If the mmap reference is the last one, the buffer_list and the associated memory can go away, since the vma insertion has references to the inserted pages at that point. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/kbuf: vmap pinned buffer ring

2025-03-22T19:50:45+00:00

Commit e270bfd22a2a10d1cfbaddf23e79b6d0b405d21e upstream. This avoids needing to care about HIGHMEM, and it makes the buffer indexing easier as both ring provided buffer methods are now virtually mapped in a contigious fashion. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring/kbuf: reallocate buf lists on upgrade

2025-02-21T12:57:27+00:00

commit 8802766324e1f5d414a81ac43365c20142e85603 upstream. IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead. Cc: stable@vger.kernel.org Reported-by: Pumpkin Chang Fixes: 2fcabce2d7d34 ("io_uring: disallow mixed provided buffer group registrations") Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

io_uring: check for non-NULL file pointer in io_file_can_poll()

2024-06-21T12:38:23+00:00

commit 5fc16fa5f13b3c06fdb959ef262050bd810416a2 upstream. In earlier kernels, it was possible to trigger a NULL pointer dereference off the forced async preparation path, if no file had been assigned. The trace leading to that looks as follows: BUG: kernel NULL pointer dereference, address: 00000000000000b0 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP CPU: 67 PID: 1633 Comm: buf-ring-invali Not tainted 6.8.0-rc3+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 2/2/2022 RIP: 0010:io_buffer_select+0xc3/0x210 Code: 00 00 48 39 d1 0f 82 ae 00 00 00 48 81 4b 48 00 00 01 00 48 89 73 70 0f b7 50 0c 66 89 53 42 85 ed 0f 85 d2 00 00 00 48 8b 13 <48> 8b 92 b0 00 00 00 48 83 7a 40 00 0f 84 21 01 00 00 4c 8b 20 5b RSP: 0018:ffffb7bec38c7d88 EFLAGS: 00010246 RAX: ffff97af2be61000 RBX: ffff97af234f1700 RCX: 0000000000000040 RDX: 0000000000000000 RSI: ffff97aecfb04820 RDI: ffff97af234f1700 RBP: 0000000000000000 R08: 0000000000200030 R09: 0000000000000020 R10: ffffb7bec38c7dc8 R11: 000000000000c000 R12: ffffb7bec38c7db8 R13: ffff97aecfb05800 R14: ffff97aecfb05800 R15: ffff97af2be5e000 FS: 00007f852f74b740(0000) GS:ffff97b1eeec0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000000b0 CR3: 000000016deab005 CR4: 0000000000370ef0 Call Trace: ? __die+0x1f/0x60 ? page_fault_oops+0x14d/0x420 ? do_user_addr_fault+0x61/0x6a0 ? exc_page_fault+0x6c/0x150 ? asm_exc_page_fault+0x22/0x30 ? io_buffer_select+0xc3/0x210 __io_import_iovec+0xb5/0x120 io_readv_prep_async+0x36/0x70 io_queue_sqe_fallback+0x20/0x260 io_submit_sqes+0x314/0x630 __do_sys_io_uring_enter+0x339/0xbc0 ? __do_sys_io_uring_register+0x11b/0xc50 ? vm_mmap_pgoff+0xce/0x160 do_syscall_64+0x5f/0x180 entry_SYSCALL_64_after_hwframe+0x46/0x4e RIP: 0033:0x55e0a110a67e Code: ba cc 00 00 00 45 31 c0 44 0f b6 92 d0 00 00 00 31 d2 41 b9 08 00 00 00 41 83 e2 01 41 c1 e2 04 41 09 c2 b8 aa 01 00 00 0f 05 90 89 30 eb a9 0f 1f 40 00 48 8b 42 20 8b 00 a8 06 75 af 85 f6 because the request is marked forced ASYNC and has a bad file fd, and hence takes the forced async prep path. Current kernels with the request async prep cleaned up can no longer hit this issue, but for ease of backporting, let's add this safety check in here too as it really doesn't hurt. For both cases, this will inevitably end with a CQE posted with -EBADF. Cc: stable@vger.kernel.org Fixes: a76c0b31eef5 ("io_uring: commit non-pollable provided mapped buffers upfront") Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman