Commit c4baad50 authored by Omar Sandoval's avatar Omar Sandoval Committed by Michael S. Tsirkin

virtio-console: avoid DMA from stack

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 <[email protected]>
Signed-off-by: default avatarMichael S. Tsirkin <[email protected]>
Reviewed-by: default avatarAmit Shah <[email protected]>
parent f8894913
......@@ -1136,6 +1136,8 @@ 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);
......@@ -1144,8 +1146,14 @@ 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);
return ret;
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