OpenE2K/linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

io_uring: fix fs->users overflow

Browse Source 
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: cac68d12c5 ("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>
This commit is contained in:
Pavel Begunkov 2022-04-14 08:50:50 +01:00 committed by Greg Kroah-Hartman
parent 33fcb359a6
commit 1a623d361f
1 changed files with 18 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
fs/io_uring.c
View File

@ -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;