6.18-stable review patch. If anyone has any objections, please let me know.
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From: Caleb Sander Mateos csander@purestorage.com
[ Upstream commit 78385c7299f7514697d196b3233a91bd5e485591 ]
The struct io_uring_buf elements in a buffer ring are in a memory region accessible from userspace. A malicious/buggy userspace program could therefore write to them at any time, so they should be accessed with READ_ONCE() in the kernel. Commit 98b6fa62c84f ("io_uring/kbuf: always use READ_ONCE() to read ring provided buffer lengths") already switched the reads of the len field to READ_ONCE(). Do the same for bid and addr.
Signed-off-by: Caleb Sander Mateos csander@purestorage.com Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Cc: Joanne Koong joannelkoong@gmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- io_uring/kbuf.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index a727e020fe036..d974381d93ff7 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -44,7 +44,7 @@ static bool io_kbuf_inc_commit(struct io_buffer_list *bl, int len) buf_len -= this_len; /* Stop looping for invalid buffer length of 0 */ if (buf_len || !this_len) { - buf->addr += this_len; + buf->addr = READ_ONCE(buf->addr) + this_len; buf->len = buf_len; return false; } @@ -198,9 +198,9 @@ static struct io_br_sel io_ring_buffer_select(struct io_kiocb *req, size_t *len, if (*len == 0 || *len > buf_len) *len = buf_len; req->flags |= REQ_F_BUFFER_RING | REQ_F_BUFFERS_COMMIT; - req->buf_index = buf->bid; + req->buf_index = READ_ONCE(buf->bid); sel.buf_list = bl; - sel.addr = u64_to_user_ptr(buf->addr); + sel.addr = u64_to_user_ptr(READ_ONCE(buf->addr));
if (io_should_commit(req, issue_flags)) { io_kbuf_commit(req, sel.buf_list, *len, 1); @@ -280,7 +280,7 @@ static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg, if (!arg->max_len) arg->max_len = INT_MAX;
- req->buf_index = buf->bid; + req->buf_index = READ_ONCE(buf->bid); do { u32 len = READ_ONCE(buf->len);
@@ -295,7 +295,7 @@ static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg, } }
- iov->iov_base = u64_to_user_ptr(buf->addr); + iov->iov_base = u64_to_user_ptr(READ_ONCE(buf->addr)); iov->iov_len = len; iov++;