The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 45e1058b77feade4e36402828bfe3e0d3363177b Mon Sep 17 00:00:00 2001 From: Dan Carpenter dan.carpenter@oracle.com Date: Wed, 20 Jul 2022 21:28:18 +0300 Subject: [PATCH] NTB: ntb_tool: uninitialized heap data in tool_fn_write()

The call to:

ret = simple_write_to_buffer(buf, size, offp, ubuf, size);

will return success if it is able to write even one byte to "buf". The value of "*offp" controls which byte. This could result in reading uninitialized data when we do the sscanf() on the next line.

This code is not really desigined to handle partial writes where *offp is non-zero and the "buf" is preserved and re-used between writes. Just ban partial writes and replace the simple_write_to_buffer() with copy_from_user().

Fixes: 578b881ba9c4 ("NTB: Add tool test client") Signed-off-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Jon Mason jdmason@kudzu.us

diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c index b7bf3f863d79..5ee0afa621a9 100644 --- a/drivers/ntb/test/ntb_tool.c +++ b/drivers/ntb/test/ntb_tool.c @@ -367,14 +367,16 @@ static ssize_t tool_fn_write(struct tool_ctx *tc, u64 bits; int n;

+ if (*offp) + return 0; + buf = kmalloc(size + 1, GFP_KERNEL); if (!buf) return -ENOMEM;

- ret = simple_write_to_buffer(buf, size, offp, ubuf, size); - if (ret < 0) { + if (copy_from_user(buf, ubuf, size)) { kfree(buf); - return ret; + return -EFAULT; }

buf[size] = 0;