From: Pavel Begunkov <asml.silence@gmail.com> mainline inclusion from mainline-5.5-rc1 commit 311ae9e159d81a1ec1cf645daf40b39ae5a0bd84 category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA --------------------------- Read/write requests to devices without implemented read/write_iter using fixed buffers can cause general protection fault, which totally hangs a machine. io_import_fixed() initialises iov_iter with bvec, but loop_rw_iter() accesses it as iovec, dereferencing random address. kmap() page by page in this case Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Signed-off-by: yangerkun <yangerkun@huawei.com> Reviewed-by: zhangyi (F) <yi.zhang@huawei.com> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> --- fs/io_uring.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 702cbb5c0d47..e4fe2c140bfb 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1621,9 +1621,19 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb, return -EAGAIN; while (iov_iter_count(iter)) { - struct iovec iovec = iov_iter_iovec(iter); + struct iovec iovec; ssize_t nr; + if (!((iter->type & ~(READ | WRITE)) == ITER_BVEC)) { + iovec = iov_iter_iovec(iter); + } else { + /* fixed buffers import bvec */ + iovec.iov_base = kmap(iter->bvec->bv_page) + + iter->iov_offset; + iovec.iov_len = min(iter->count, + iter->bvec->bv_len - iter->iov_offset); + } + if (rw == READ) { nr = file->f_op->read(file, iovec.iov_base, iovec.iov_len, &kiocb->ki_pos); @@ -1632,6 +1642,9 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb, iovec.iov_len, &kiocb->ki_pos); } + if ((iter->type & ~(READ | WRITE)) == ITER_BVEC) + kunmap(iter->bvec->bv_page); + if (nr < 0) { if (!ret) ret = nr; -- 2.25.1