Re: [PATCH net] xfrm: fix integer overflow in xfrm_replay_state_esn_len()

[Dan Carpenter <dan.carpenter@linaro.org>]

I've added linux-hardening to the CC.

This is a fortify false positive.  I can't reproduce it on x86 with
gcc-14.  Perhaps it only affect mips?  It's a W=1 warning so it shouldn't
be a blocker in that sense.

regards,
dan carpenter

On Thu, Jan 23, 2025 at 12:53:14AM +0800, kernel test robot wrote:
> Hi Dan,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on net/main]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Dan-Carpenter/xfrm-fix-integer-overflow-in-xfrm_replay_state_esn_len/20250121-191827
> base:   net/main
> patch link:    https://lore.kernel.org/r/018ecf13-e371-4b39-8946-c7510baf916b%40stanley.mountain
> patch subject: [PATCH net] xfrm: fix integer overflow in xfrm_replay_state_esn_len()
> config: mips-allyesconfig (https://download.01.org/0day-ci/archive/20250123/202501230035.cFbLTHtZ-lkp@intel.com/config)
> compiler: mips-linux-gcc (GCC) 14.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250123/202501230035.cFbLTHtZ-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202501230035.cFbLTHtZ-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>    In file included from include/linux/string.h:389,
>                     from include/linux/bitmap.h:13,
>                     from include/linux/cpumask.h:12,
>                     from arch/mips/include/asm/processor.h:15,
>                     from arch/mips/include/asm/thread_info.h:16,
>                     from include/linux/thread_info.h:60,
>                     from include/asm-generic/preempt.h:5,
>                     from ./arch/mips/include/generated/asm/preempt.h:1,
>                     from include/linux/preempt.h:79,
>                     from include/linux/spinlock.h:56,
>                     from include/net/xfrm.h:7,
>                     from net/xfrm/xfrm_replay.c:10:
>    In function 'memcmp',
>        inlined from 'xfrm_replay_notify_bmp' at net/xfrm/xfrm_replay.c:336:7:
> >> include/linux/fortify-string.h:120:33: warning: '__builtin_memcmp' specified bound 4294967295 exceeds maximum object size 2147483647 [-Wstringop-overread]
>      120 | #define __underlying_memcmp     __builtin_memcmp
>          |                                 ^
>    include/linux/fortify-string.h:727:16: note: in expansion of macro '__underlying_memcmp'
>      727 |         return __underlying_memcmp(p, q, size);
>          |                ^~~~~~~~~~~~~~~~~~~
>    net/xfrm/xfrm_replay.c: In function 'xfrm_replay_notify_bmp':
>    net/xfrm/xfrm_replay.c:308:53: note: source object allocated here
>      308 |         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
>          |                                                    ~^~~~~~~~~~~~
>    In function 'memcmp',
>        inlined from 'xfrm_replay_notify_esn' at net/xfrm/xfrm_replay.c:402:7:
> >> include/linux/fortify-string.h:120:33: warning: '__builtin_memcmp' specified bound 4294967295 exceeds maximum object size 2147483647 [-Wstringop-overread]
>      120 | #define __underlying_memcmp     __builtin_memcmp
>          |                                 ^
>    include/linux/fortify-string.h:727:16: note: in expansion of macro '__underlying_memcmp'
>      727 |         return __underlying_memcmp(p, q, size);
>          |                ^~~~~~~~~~~~~~~~~~~
>    net/xfrm/xfrm_replay.c: In function 'xfrm_replay_notify_esn':
>    net/xfrm/xfrm_replay.c:360:53: note: source object allocated here
>      360 |         struct xfrm_replay_state_esn *replay_esn = x->replay_esn;
>          |                                                    ~^~~~~~~~~~~~
> 
> 
> vim +/__builtin_memcmp +120 include/linux/fortify-string.h
> 
> 78a498c3a227f2 Alexander Potapenko 2022-10-24  118  
> 78a498c3a227f2 Alexander Potapenko 2022-10-24  119  #define __underlying_memchr	__builtin_memchr
> 78a498c3a227f2 Alexander Potapenko 2022-10-24 @120  #define __underlying_memcmp	__builtin_memcmp
> a28a6e860c6cf2 Francis Laniel      2021-02-25  121  #define __underlying_strcat	__builtin_strcat
> a28a6e860c6cf2 Francis Laniel      2021-02-25  122  #define __underlying_strcpy	__builtin_strcpy
> a28a6e860c6cf2 Francis Laniel      2021-02-25  123  #define __underlying_strlen	__builtin_strlen
> a28a6e860c6cf2 Francis Laniel      2021-02-25  124  #define __underlying_strncat	__builtin_strncat
> a28a6e860c6cf2 Francis Laniel      2021-02-25  125  #define __underlying_strncpy	__builtin_strncpy
> 2e577732e8d28b Andrey Konovalov    2024-05-17  126  
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki