From: Gabriel Krisman Bertazi krisman@collabora.com
[ Upstream commit 6e682d53fc1ef73a169e2a5300326cb23abb32ee ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/um/drivers/ubd_kern.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index 6627d7c30f370..0f5d0a699a49b 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1606,7 +1606,9 @@ 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; }