Commit 0dd8a470 authored by Omar Sandoval's avatar Omar Sandoval Committed by Sasha Levin

virtio-console: avoid DMA from stack

[ Upstream commit c4baad50 ]

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>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent eb618d2e
...@@ -1130,6 +1130,8 @@ static int put_chars(u32 vtermno, const char *buf, int count) ...@@ -1130,6 +1130,8 @@ static int put_chars(u32 vtermno, const char *buf, int count)
{ {
struct port *port; struct port *port;
struct scatterlist sg[1]; struct scatterlist sg[1];
void *data;
int ret;
if (unlikely(early_put_chars)) if (unlikely(early_put_chars))
return early_put_chars(vtermno, buf, count); return early_put_chars(vtermno, buf, count);
...@@ -1138,8 +1140,14 @@ static int put_chars(u32 vtermno, const char *buf, int count) ...@@ -1138,8 +1140,14 @@ static int put_chars(u32 vtermno, const char *buf, int count)
if (!port) if (!port)
return -EPIPE; return -EPIPE;
sg_init_one(sg, buf, count); data = kmemdup(buf, count, GFP_ATOMIC);
return __send_to_port(port, sg, 1, count, (void *)buf, false); 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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