Commit eb526765 authored by Omar Sandoval's avatar Omar Sandoval Committed by Greg Kroah-Hartman

virtio-console: avoid DMA from stack

commit c4baad50 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: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarAmit Shah <amit.shah@redhat.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6be431f9
......@@ -1130,6 +1130,8 @@ 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);
......@@ -1138,8 +1140,14 @@ 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;
}
/*
......
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