um: ubd: Prevent buffer overrun on command completion

On the hypervisor side, when completing commands and the pipe is full,
we retry writing only the entries that failed, by offsetting
io_req_buffer, but we don't reduce the number of bytes written, which
can cause a buffer overrun of io_req_buffer, and write garbage to the
pipe.

Cc: Martyn Welch <martyn.welch@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Gabriel Krisman Bertazi 2020-03-16 20:45:06 -04:00 committed by Richard Weinberger
parent 598f563036
commit 6e682d53fc

View File

@ -1607,7 +1607,9 @@ int io_thread(void *arg)
written = 0;
do {
res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n);
res = os_write_file(kernel_fd,
((char *) io_req_buffer) + written,
n - written);
if (res >= 0) {
written += res;
}