diff options
author | Pavel Begunkov <asml.silence@gmail.com> | 2022-04-14 08:50:50 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-15 14:18:41 +0200 |
commit | 1a623d361ffe5cecd4244a02f449528416360038 (patch) | |
tree | b99709904f01723c8475b87507637b4427b9c94c /fs | |
parent | 33fcb359a64213bea0510770abc761de9780ca89 (diff) |
io_uring: fix fs->users overflow
There is a bunch of cases where we can grab req->fs but not put it, this
can be used to cause a controllable overflow with further implications.
Release req->fs in the request free path and make sure we zero the field
to be sure we don't do it twice.
Fixes: cac68d12c531 ("io_uring: grab ->fs as part of async offload")
Reported-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/io_uring.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 478df7e10767..e73969fa96bc 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -438,6 +438,22 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) return ctx; } +static void io_req_put_fs(struct io_kiocb *req) +{ + struct fs_struct *fs = req->fs; + + if (!fs) + return; + + spin_lock(&req->fs->lock); + if (--fs->users) + fs = NULL; + spin_unlock(&req->fs->lock); + if (fs) + free_fs_struct(fs); + req->fs = NULL; +} + static inline bool __io_sequence_defer(struct io_ring_ctx *ctx, struct io_kiocb *req) { @@ -695,6 +711,7 @@ static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr) static void __io_free_req(struct io_kiocb *req) { + io_req_put_fs(req); if (req->file && !(req->flags & REQ_F_FIXED_FILE)) fput(req->file); percpu_ref_put(&req->ctx->refs); @@ -1701,16 +1718,7 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe, ret = -EINTR; } - if (req->fs) { - struct fs_struct *fs = req->fs; - - spin_lock(&req->fs->lock); - if (--fs->users) - fs = NULL; - spin_unlock(&req->fs->lock); - if (fs) - free_fs_struct(fs); - } + io_req_put_fs(req); io_cqring_add_event(req->ctx, sqe->user_data, ret); io_put_req(req); return 0; |