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| author | Pavel Begunkov <asml.silence@gmail.com> | 2020-06-27 14:04:56 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-06-28 08:10:17 -0600 |
| commit | 1bcb8c5d65a845e0ecb9e82237c399b29b8d15ea (patch) | |
| tree | f93bb3194f36557ae83383405e0b9556d69200aa /fs/io_uring.c | |
| parent | 906a8c3fdbc367325d4200e39212a2a7715b7b0e (diff) | |
| download | lwn-1bcb8c5d65a845e0ecb9e82237c399b29b8d15ea.tar.gz lwn-1bcb8c5d65a845e0ecb9e82237c399b29b8d15ea.zip | |
io_uring: fix feeding io-wq with uninit reqs
io_steal_work() can't be sure that @nxt has req->work properly set, so we
can't pass it to io-wq as is.
A dirty quick fix -- drag it through io_req_task_queue(), and always
return NULL from io_steal_work().
e.g.
[ 50.770161] BUG: kernel NULL pointer dereference, address: 00000000
[ 50.770164] #PF: supervisor write access in kernel mode
[ 50.770164] #PF: error_code(0x0002) - not-present page
[ 50.770168] CPU: 1 PID: 1448 Comm: io_wqe_worker-0 Tainted: G
I 5.8.0-rc2-00035-g2237d76530eb-dirty #494
[ 50.770172] RIP: 0010:override_creds+0x19/0x30
...
[ 50.770183] io_worker_handle_work+0x25c/0x430
[ 50.770185] io_wqe_worker+0x2a0/0x350
[ 50.770190] kthread+0x136/0x180
[ 50.770194] ret_from_fork+0x22/0x30
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 483457f6a7df..658949bed77f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1791,7 +1791,7 @@ static void io_put_req(struct io_kiocb *req) static struct io_wq_work *io_steal_work(struct io_kiocb *req) { - struct io_kiocb *link, *nxt = NULL; + struct io_kiocb *nxt = NULL; /* * A ref is owned by io-wq in which context we're. So, if that's the @@ -1808,10 +1808,15 @@ static struct io_wq_work *io_steal_work(struct io_kiocb *req) if ((nxt->flags & REQ_F_ISREG) && io_op_defs[nxt->opcode].hash_reg_file) io_wq_hash_work(&nxt->work, file_inode(nxt->file)); - link = io_prep_linked_timeout(nxt); - if (link) - nxt->flags |= REQ_F_QUEUE_TIMEOUT; - return &nxt->work; + io_req_task_queue(nxt); + /* + * If we're going to return actual work, here should be timeout prep: + * + * link = io_prep_linked_timeout(nxt); + * if (link) + * nxt->flags |= REQ_F_QUEUE_TIMEOUT; + */ + return NULL; } /* |