On 11/21/24 7:08 AM, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 43fb83c17ba2 Merge tag 'soc-arm-6.13' of git://git.kernel... > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=134feb78580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=9f17942989df952c > dashboard link: https://syzkaller.appspot.com/bug?extid=9a8500a45c2cabdf9577 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f767f7980000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f50ec0580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/e1e82262b7ac/disk-43fb83c1.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/7ca6e1c46dc5/vmlinux-43fb83c1.xz > kernel image: https://storage.googleapis.com/syzbot-assets/63aaea837532/bzImage-43fb83c1.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+9a8500a45c2cabdf9577@xxxxxxxxxxxxxxxxxxxxxxxxx > > ===================================================== > BUG: KMSAN: uninit-value in io_nop+0x549/0x8a0 io_uring/nop.c:55 > io_nop+0x549/0x8a0 io_uring/nop.c:55 > io_issue_sqe+0x420/0x2130 io_uring/io_uring.c:1712 > io_queue_sqe io_uring/io_uring.c:1922 [inline] > io_submit_sqe io_uring/io_uring.c:2177 [inline] > io_submit_sqes+0x11bc/0x2f80 io_uring/io_uring.c:2294 > __do_sys_io_uring_enter io_uring/io_uring.c:3365 [inline] > __se_sys_io_uring_enter+0x423/0x4aa0 io_uring/io_uring.c:3300 > __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3300 > x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > Uninit was created at: > __alloc_pages_noprof+0x9a7/0xe00 mm/page_alloc.c:4774 > alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2265 > alloc_pages_noprof+0x1bf/0x1e0 mm/mempolicy.c:2345 > alloc_slab_page mm/slub.c:2412 [inline] > allocate_slab+0x320/0x12e0 mm/slub.c:2578 > new_slab mm/slub.c:2631 [inline] > ___slab_alloc+0x12ef/0x35e0 mm/slub.c:3818 > __kmem_cache_alloc_bulk mm/slub.c:4895 [inline] > kmem_cache_alloc_bulk_noprof+0x486/0x1330 mm/slub.c:4967 > __io_alloc_req_refill+0x84/0x5b0 io_uring/io_uring.c:958 > io_alloc_req io_uring/io_uring.h:411 [inline] > io_submit_sqes+0x9a2/0x2f80 io_uring/io_uring.c:2283 > __do_sys_io_uring_enter io_uring/io_uring.c:3365 [inline] > __se_sys_io_uring_enter+0x423/0x4aa0 io_uring/io_uring.c:3300 > __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3300 > x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f Yep that's a bug introduced in this merge window, the below should fix it: commit ee116574de8415b0673c466e6cd28ba5f70c41a2 Author: Jens Axboe <axboe@xxxxxxxxx> Date: Thu Nov 21 07:12:17 2024 -0700 io_uring/nop: ensure nop->fd is always initialized A previous commit added file support for nop, but it only initializes nop->fd if IORING_NOP_FIXED_FILE is set. That check should be IORING_NOP_FILE. Fix up the condition in nop preparation, and initialize it to a sane value even if we're not going to be directly using it. While in there, do the same thing for the nop->buffer field. Reported-by: syzbot+9a8500a45c2cabdf9577@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: a85f31052bce ("io_uring/nop: add support for testing registered files and buffers") Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> diff --git a/io_uring/nop.c b/io_uring/nop.c index 6d470d4251ee..5e5196df650a 100644 --- a/io_uring/nop.c +++ b/io_uring/nop.c @@ -35,10 +35,14 @@ int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) nop->result = READ_ONCE(sqe->len); else nop->result = 0; - if (nop->flags & IORING_NOP_FIXED_FILE) + if (nop->flags & IORING_NOP_FILE) nop->fd = READ_ONCE(sqe->fd); + else + nop->fd = -1; if (nop->flags & IORING_NOP_FIXED_BUFFER) nop->buffer = READ_ONCE(sqe->buf_index); + else + nop->buffer = -1; return 0; } -- Jens Axboe
