From: Omar Sandoval <osandov@osandov.com> To: Amit Shah <amit.shah@redhat.com> Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH] virtio-console: avoid DMA from stack Date: Wed, 1 Feb 2017 00:02:27 -0800 [thread overview] Message-ID: <075115ddd99246ffc4228a3e050ba68eb36c6a8c.1485935920.git.osandov@fb.com> (raw) From: Omar Sandoval <osandov@fb.com> 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> --- Patch based on v4.10-rc6. drivers/char/virtio_console.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 17857beb4892..3cbf4c95e446 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -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); + kfree(data); + return ret; } /* -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Omar Sandoval <osandov@osandov.com> To: Amit Shah <amit.shah@redhat.com> Cc: kernel-team@fb.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH] virtio-console: avoid DMA from stack Date: Wed, 1 Feb 2017 00:02:27 -0800 [thread overview] Message-ID: <075115ddd99246ffc4228a3e050ba68eb36c6a8c.1485935920.git.osandov@fb.com> (raw) From: Omar Sandoval <osandov@fb.com> 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> --- Patch based on v4.10-rc6. drivers/char/virtio_console.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 17857beb4892..3cbf4c95e446 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -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); + kfree(data); + return ret; } /* -- 2.11.0
next reply other threads:[~2017-02-01 8:03 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-02-01 8:02 Omar Sandoval [this message] 2017-02-01 8:02 ` [PATCH] virtio-console: avoid DMA from stack Omar Sandoval 2017-02-01 13:47 ` Amit Shah 2017-02-01 13:47 ` Amit Shah 2017-03-01 20:01 ` Omar Sandoval 2017-03-01 20:01 ` Omar Sandoval 2017-03-01 21:25 ` Michael S. Tsirkin 2017-03-01 21:25 ` Michael S. Tsirkin 2017-03-03 0:58 ` Jan Dakinevich 2017-03-03 0:58 ` Jan Dakinevich
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