From: Omar Sandoval Date: Wed, 1 Feb 2017 08:02:27 +0000 (-0800) Subject: virtio-console: avoid DMA from stack X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=146a68802ce10c459c5f7dea49d199ee1b7a5755;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git 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 Signed-off-by: Michael S. Tsirkin Reviewed-by: Amit Shah Cc: Ben Hutchings Cc: Brad Spengler Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index ec3bd62eeaf..d69c63fdae6 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1129,6 +1129,8 @@ 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); @@ -1137,8 +1139,14 @@ 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; } /*