diff options
| author | Vasileios Almpanis <vasilisalmpanis@gmail.com> | 2026-06-15 16:45:57 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-06-16 06:20:01 -0600 |
| commit | 2564ca2e31bd8ee8348362941af2ee4671e487ca (patch) | |
| tree | 963fbc91387b957fd47847b514a703ceb328fe69 | |
| parent | 8b308f96484e37d92d2fc6b72b091f60496c000e (diff) | |
io_uring/nop: fix file reference leak with IOSQE_FIXED_FILE
NOP file-acquisition support choses between a fixed (registered) file and
a normal fget()'d file based on its own IORING_NOP_FIXED_FILE flag in
sqe->nop_flags. However, a request's REQ_F_FIXED_FILE is set
independently from the generic IOSQE_FIXED_FILE sqe flag during request
init, before the issue handler runs.
If a NOP is submitted with IOSQE_FIXED_FILE set (so REQ_F_FIXED_FILE is
set) but without IORING_NOP_FIXED_FILE, io_nop() takes the normal path
and grabs a real reference via io_file_get_normal(). On completion,
io_put_file() only drops the reference when REQ_F_FIXED_FILE is clear,
so the fget()'d file is never released and leaks:
BUG: memory leak
unreferenced object 0xffff88800f42c240 (size 176):
kmem_cache_alloc_noprof+0x358/0x440
alloc_empty_file+0x57/0x180
path_openat+0x44/0x1e50
do_file_open+0x121/0x200
do_sys_openat2+0xa7/0x150
__x64_sys_openat+0x82/0xf0
Decide between fixed and normal file acquisition from REQ_F_FIXED_FILE,
the same way io_assign_file() does for every other opcode, and fold
IORING_NOP_FIXED_FILE into REQ_F_FIXED_FILE at prep time.
Cc: stable@vger.kernel.org
Fixes: a85f31052bce ("io_uring/nop: add support for testing registered files and buffers")
Reported-by: syzbot+2cd473471e77bda12b0e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?id=879092631b98f73a28ea405adacfa5bb34a14a25
Signed-off-by: Vasileios Almpanis <vasilisalmpanis@gmail.com>
Link: https://patch.msgid.link/20260615144619.482749-1-vasilisalmpanis@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/nop.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/io_uring/nop.c b/io_uring/nop.c index 91ae0b2e7e55..60ab19604b36 100644 --- a/io_uring/nop.c +++ b/io_uring/nop.c @@ -40,6 +40,8 @@ int io_nop_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) nop->fd = READ_ONCE(sqe->fd); else nop->fd = -1; + if (nop->flags & IORING_NOP_FIXED_FILE) + req->flags |= REQ_F_FIXED_FILE; if (nop->flags & IORING_NOP_FIXED_BUFFER) req->buf_index = READ_ONCE(sqe->buf_index); if (nop->flags & IORING_NOP_CQE32) { @@ -59,12 +61,10 @@ int io_nop(struct io_kiocb *req, unsigned int issue_flags) int ret = nop->result; if (nop->flags & IORING_NOP_FILE) { - if (nop->flags & IORING_NOP_FIXED_FILE) { + if (req->flags & REQ_F_FIXED_FILE) req->file = io_file_get_fixed(req, nop->fd, issue_flags); - req->flags |= REQ_F_FIXED_FILE; - } else { + else req->file = io_file_get_normal(req, nop->fd); - } if (!req->file) { ret = -EBADF; goto done; |