This is a note to let you know that I've just added the patch titled
virtio-console: avoid DMA from stack
to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio-console-avoid-dma-from-stack.patch
and it can be found in the queue-4.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c4baad50297d84bde1a7ad45e50c73adae4a2192 Mon Sep 17 00:00:00 2001
From: Omar Sandoval <osandov@xxxxxx>
Date: Wed, 1 Feb 2017 00:02:27 -0800
Subject: virtio-console: avoid DMA from stack
From: Omar Sandoval <osandov@xxxxxx>
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@xxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Amit Shah <amit.shah@xxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Brad Spengler <spender@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/char/virtio_console.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1136,6 +1136,8 @@ static int put_chars(u32 vtermno, const
{
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
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;
}
/*
Patches currently in stable-queue which might be from osandov@xxxxxx are
queue-4.10/x86-efi-don-t-try-to-reserve-runtime-regions.patch
queue-4.10/virtio-console-avoid-dma-from-stack.patch