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| author | Omar Sandoval <osandov@fb.com> | 2017-02-01 00:02:27 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-06-05 21:17:22 +0100 |
| commit | 86222aa6b2ff9e5ba81d272d809b7401144548f0 (patch) | |
| tree | 70c6466611bfb9a0a0fc7245686fbb51a1ad963e /drivers | |
| parent | 522182342410708c54eb2b33ff36e85f0b045a6d (diff) | |
| download | linux-stable-86222aa6b2ff9e5ba81d272d809b7401144548f0.tar.gz linux-stable-86222aa6b2ff9e5ba81d272d809b7401144548f0.tar.bz2 linux-stable-86222aa6b2ff9e5ba81d272d809b7401144548f0.zip | |
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'drivers')
| -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 7d58b2918138..f56ea682ad44 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; } /* |