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1a2fb220ed
Under both -Warray-bounds and the object_size sanitizer, the compiler is
upset about accessing prev/next of sk_buff when the object it thinks it
is coming from is sk_buff_head. The warning is a false positive due to
the compiler taking a conservative approach, opting to warn at casting
time rather than access time.
However, in support of enabling -Warray-bounds globally (which has
found many real bugs), arrange things for sk_buff so that the compiler
can unambiguously see that there is no intention to access anything
except prev/next. Introduce and cast to a separate struct sk_buff_list,
which contains _only_ the first two fields, silencing the warnings:
In file included from ./include/net/net_namespace.h:39,
from ./include/linux/netdevice.h:37,
from net/core/netpoll.c:17:
net/core/netpoll.c: In function 'refill_skbs':
./include/linux/skbuff.h:2086:9: warning: array subscript 'struct sk_buff[0]' is partly outside array bounds of 'struct sk_buff_head[1]' [-Warray-bounds]
2086 | __skb_insert(newsk, next->prev, next, list);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/core/netpoll.c:49:28: note: while referencing 'skb_pool'
49 | static struct sk_buff_head skb_pool;
| ^~~~~~~~
This change results in no executable instruction differences.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211207062758.2324338-1-keescook@chromium.org
Signed-off-by: Jakub Kicinski <kuba@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.