From 6d2f75a0cf3048ef38c48493f66a923353bf664b Mon Sep 17 00:00:00 2001
From: Dylan Yudaken <dylany@fb.com>
Date: Fri, 8 Jul 2022 11:18:36 -0700
Subject: [PATCH] io_uring: support 0 length iov in buffer select in compat
Match up work done in "io_uring: allow iov_len = 0 for recvmsg and buffer
select", but for compat code path.
Fixes: a68caad69ce5 ("io_uring: allow iov_len = 0 for recvmsg and buffer select")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220708181838.1495428-3-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/net.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/io_uring/net.c b/io_uring/net.c
index eb939899e9c5a..dc9190eafbe70 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -382,16 +382,21 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
if (req->flags & REQ_F_BUFFER_SELECT) {
compat_ssize_t clen;
- if (len > 1)
- return -EINVAL;
- if (!access_ok(uiov, sizeof(*uiov)))
- return -EFAULT;
- if (__get_user(clen, &uiov->iov_len))
- return -EFAULT;
- if (clen < 0)
+ if (len == 0) {
+ sr->len = 0;
+ iomsg->free_iov = NULL;
+ } else if (len > 1) {
return -EINVAL;
- sr->len = clen;
- iomsg->free_iov = NULL;
+ } else {
+ if (!access_ok(uiov, sizeof(*uiov)))
+ return -EFAULT;
+ if (__get_user(clen, &uiov->iov_len))
+ return -EFAULT;
+ if (clen < 0)
+ return -EINVAL;
+ sr->len = clen;
+ iomsg->free_iov = NULL;
+ }
} else {
iomsg->free_iov = iomsg->fast_iov;
ret = __import_iovec(READ, (struct iovec __user *)uiov, len,