diff options
| author | Omar Sandoval <osandov@fb.com> | 2017-02-01 00:02:27 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-21 09:31:24 +0200 |
| commit | 86c6667f6a5f6bdb392d8ffbe58fbcbcf6db2704 (patch) | |
| tree | 735cdb27c467f3899a5b92e3957063ec31635de8 | |
| parent | fb00319317c152bf3528df13a54c28bf8c5daa55 (diff) | |
virtio-console: avoid DMA from stack
commit c4baad50297d84bde1a7ad45e50c73adae4a2192 upstream.
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>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 5649234b7316..471a301d63e3 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; } /* |