nbufs tracks the number of buffers and not the last bgid. In 16-bit, we
have 2^16 valid buffers, but the check mistakenly rejects the last
bid. Let's fix it to make the interface consistent with the
documentation.
Fixes: ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxx>
---
io_uring/kbuf.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 52dba81c3f50..12a357348733 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -19,12 +19,15 @@
#define BGID_ARRAY 64
+/* BIDs are addressed by a 16-bit field in a CQE */
+#define MAX_BIDS_PER_BGID (1 << 16)
+
struct io_provide_buf {
struct file *file;
__u64 addr;
__u32 len;
__u32 bgid;
- __u16 nbufs;
+ __u32 nbufs;
__u16 bid;
};
@@ -289,7 +292,7 @@ int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
return -EINVAL;
tmp = READ_ONCE(sqe->fd);
- if (!tmp || tmp > USHRT_MAX)
+ if (!tmp || tmp > MAX_BIDS_PER_BGID)
return -EINVAL;
memset(p, 0, sizeof(*p));
@@ -332,7 +335,7 @@ int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
return -EINVAL;
tmp = READ_ONCE(sqe->fd);
- if (!tmp || tmp > USHRT_MAX)
+ if (!tmp || tmp > MAX_BIDS_PER_BGID)
return -E2BIG;
p->nbufs = tmp;
p->addr = READ_ONCE(sqe->addr);
@@ -352,7 +355,7 @@ int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
tmp = READ_ONCE(sqe->off);
if (tmp > USHRT_MAX)
return -E2BIG;
- if (tmp + p->nbufs > USHRT_MAX)
+ if (tmp + p->nbufs > MAX_BIDS_PER_BGID)
return -EINVAL;
p->bid = tmp;
return 0;
--
2.42.0
