diff options
| author | Omar Sandoval <osandov@fb.com> | 2017-02-01 00:02:27 -0800 |
|---|---|---|
| committer | Sasha Levin <alexander.levin@verizon.com> | 2017-06-13 09:29:17 -0400 |
| commit | 0dd8a4702cbc9730ab923720db298c0febd91914 (patch) | |
| tree | c6678af3845d9bd8e0634996d5a868f1d567efc1 /drivers/char | |
| parent | eb618d2eb22bb0e1843fb17431fdd18253918cb8 (diff) | |
virtio-console: avoid DMA from stack
[ Upstream commit c4baad50297d84bde1a7ad45e50c73adae4a2192 ]
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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Diffstat (limited to 'drivers/char')
| -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 8cc67132d55d..810b171b55b7 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -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; } /* |