linux-hardening - [PATCH v3 0/2] bitmap: Fix return values to be unsigned

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Date:   Wed, 18 May 2022 13:52:21 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Christophe de Dinechin <dinechin@...hat.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zhen Lei <thunder.leizhen@...wei.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH v3 0/2] bitmap: Fix return values to be unsigned

Hi,

v1: https://lore.kernel.org/lkml/20220517035411.31144-1-keescook@chromium.org
v2: https://lore.kernel.org/lkml/20220517212234.868181-1-keescook@chromium.org
v3:
 - Update missed int variable to unsigned int
 - Update tools/ bitmaps code to match
 - Adjust whitespace a bit

Rationale repeated from the last patch:

Both nodemask and bitmap routines had mixed return values that provided
potentially signed results that could never happen. This was leading to
the compiler getting confusing about the range of possible return values
(it was thinking things could be negative where they could not be). Fix
all the nodemask and bitmap routines that should be returning unsigned
(or bool) values. Silences GCC 12 warnings:

 mm/swapfile.c: In function ‘setup_swap_info’:
 mm/swapfile.c:2291:47: error: array subscript -1 is below array bounds of ‘struct plist_node[]’ [-Werror=array-bounds]
  2291 |                                 p->avail_lists[i].prio = 1;
       |                                 ~~~~~~~~~~~~~~^~~
 In file included from mm/swapfile.c:16:
 ./include/linux/swap.h:292:27: note: while referencing ‘avail_lists’
   292 |         struct plist_node avail_lists[]; /*
       |                           ^~~~~~~~~~~


I note that Alexey and Rasmus have touched on this area in the past,
fixing up node ids to be unsigned:

ce0725f78a56 ("numa: make "nr_online_nodes" unsigned int")
b9726c26dc21 ("numa: make "nr_node_ids" unsigned int")
33c4fa8c6763 ("linux/nodemask.h: update bitmap wrappers to take unsigned int")

-Kees


Kees Cook (2):
  bitmap: Fix return values to be unsigned
  nodemask: Fix return values to be unsigned

 include/linux/bitmap.h       | 25 ++++++++++++------------
 include/linux/nodemask.h     | 38 ++++++++++++++++++------------------
 lib/bitmap.c                 | 30 ++++++++++++++--------------
 lib/nodemask.c               |  4 ++--
 tools/include/linux/bitmap.h | 17 ++++++++--------
 tools/lib/bitmap.c           | 20 +++++++++----------
 6 files changed, 68 insertions(+), 66 deletions(-)

-- 
2.32.0