e2d10f1de1
[ Upstream commit 6b47808f223c70ff564f9b363446d2a5fa1e05b2 ]
TLS records end with a 16B tag. For TLS device offload we only
need to make space for this tag in the stream, the device will
generate and replace it with the actual calculated tag.
Long time ago the code would just re-reference the head frag
which mostly worked but was suboptimal because it prevented TCP
from combining the record into a single skb frag. I'm not sure
if it was correct as the first frag may be shorter than the tag.
The commit under fixes tried to replace that with using the page
frag and if the allocation failed rolling back the data, if record
was long enough. It achieves better fragment coalescing but is
also buggy.
We don't roll back the iterator, so unless we're at the end of
send we'll skip the data we designated as tag and start the
next record as if the rollback never happened.
There's also the possibility that the record was constructed
with MSG_MORE and the data came from a different syscall and
we already told the user space that we "got it".
Allocate a single dummy page and use it as fallback.
Found by code inspection, and proven by forcing allocation
failures.
Fixes: e7b159a48ba6 ("net/tls: remove the record tail optimization")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.