Gustavo A. R. Silva 323e0cb473 flow_dissector: Fix out-of-bounds warnings
Fix the following out-of-bounds warnings:

    net/core/flow_dissector.c: In function '__skb_flow_dissect':
>> net/core/flow_dissector.c:1104:4: warning: 'memcpy' offset [24, 39] from the object at '<unknown>' is out of the bounds of referenced subobject 'saddr' with type 'struct in6_addr' at offset 8 [-Warray-bounds]
     1104 |    memcpy(&key_addrs->v6addrs, &iph->saddr,
          |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1105 |           sizeof(key_addrs->v6addrs));
          |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In file included from include/linux/ipv6.h:5,
                     from net/core/flow_dissector.c:6:
    include/uapi/linux/ipv6.h:133:18: note: subobject 'saddr' declared here
      133 |  struct in6_addr saddr;
          |                  ^~~~~
>> net/core/flow_dissector.c:1059:4: warning: 'memcpy' offset [16, 19] from the object at '<unknown>' is out of the bounds of referenced subobject 'saddr' with type 'unsigned int' at offset 12 [-Warray-bounds]
     1059 |    memcpy(&key_addrs->v4addrs, &iph->saddr,
          |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     1060 |           sizeof(key_addrs->v4addrs));
          |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In file included from include/linux/ip.h:17,
                     from net/core/flow_dissector.c:5:
    include/uapi/linux/ip.h:103:9: note: subobject 'saddr' declared here
      103 |  __be32 saddr;
          |         ^~~~~

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy().  So, the compiler legitimately complains about it. As these
are just a couple of members, fix this by copying each one of them in
separate calls to memcpy().

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/d5ae2e65-1f18-2577-246f-bada7eee6ccd@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-07-26 23:02:59 +01:00
…
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2021-07-18 14:13:49 -07:00
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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.
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