diff options
| author | Omar Sandoval <osandov@fb.com> | 2017-02-01 00:02:27 -0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2017-03-02 01:35:06 +0200 |
| commit | c4baad50297d84bde1a7ad45e50c73adae4a2192 (patch) | |
| tree | 2efdf37fc4b48748d19ed2e3cb8a75908581fd26 | |
| parent | f889491380582b4ba2981cf0b0d7d6a40fb30ab7 (diff) | |
| download | linux-c4baad50297d84bde1a7ad45e50c73adae4a2192.tar.bz2 | |
virtio-console: avoid DMA from stack
put_chars() stuffs the buffer it gets into an sg, but that buffer may be
on the stack. This breaks with CONFIG_VMAP_STACK=y (for me, it
manifested as printks getting turned into NUL bytes).
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
| -rw-r--r-- | drivers/char/virtio_console.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 6266c0568e1d..e9b7e0b3cabe 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1136,6 +1136,8 @@ static int put_chars(u32 vtermno, const char *buf, int count) { struct port *port; struct scatterlist sg[1]; + void *data; + int ret; if (unlikely(early_put_chars)) return early_put_chars(vtermno, buf, count); @@ -1144,8 +1146,14 @@ static int put_chars(u32 vtermno, const char *buf, int count) if (!port) return -EPIPE; - sg_init_one(sg, buf, count); - return __send_to_port(port, sg, 1, count, (void *)buf, false); + data = kmemdup(buf, count, GFP_ATOMIC); + if (!data) + return -ENOMEM; + + sg_init_one(sg, data, count); + ret = __send_to_port(port, sg, 1, count, data, false); + kfree(data); + return ret; } /* |