[linux-next:master 4615/9759] drivers/fpga/zynq-fpga.c:245 zynq_fpga_has_sync() warn: impossible condition '(buf[2] == 153) => ((-128)-127 == 153)'

From: kernel test robot <lkp@intel.com>
To: kbuild@lists.01.org
Subject: [linux-next:master 4615/9759] drivers/fpga/zynq-fpga.c:245 zynq_fpga_has_sync() warn: impossible condition '(buf[2] == 153) => ((-128)-127 == 153)'
Date: Sun, 08 May 2022 23:34:55 +0800	[thread overview]
Message-ID: <202205082354.VLuo1EgB-lkp@intel.com> (raw)

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CC: kbuild-all(a)lists.01.org
BCC: lkp(a)intel.com
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Nava kishore Manne <nava.manne@xilinx.com>
CC: Moritz Fischer <mdf@kernel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   38a288f5941ef03752887ad86f2d85442358c99a
commit: ada14a023a641107da1ada546e1d345ca3dc78a5 [4615/9759] fpga: zynq: Fix incorrect variable type
:::::: branch date: 2 days ago
:::::: commit date: 2 weeks ago
config: csky-randconfig-m031-20220508 (https://download.01.org/0day-ci/archive/20220508/202205082354.VLuo1EgB-lkp(a)intel.com/config)
compiler: csky-linux-gcc (GCC) 11.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
drivers/fpga/zynq-fpga.c:245 zynq_fpga_has_sync() warn: impossible condition '(buf[2] == 153) => ((-128)-127 == 153)'

Old smatch warnings:
drivers/fpga/zynq-fpga.c:246 zynq_fpga_has_sync() warn: impossible condition '(buf[3] == 170) => ((-128)-127 == 170)'

vim +245 drivers/fpga/zynq-fpga.c

37784706bf9e3b Moritz Fischer     2015-10-16  237  
b496df86ac1bbe Jason Gunthorpe    2017-02-01  238  /* Sanity check the proposed bitstream. It must start with the sync word in
b496df86ac1bbe Jason Gunthorpe    2017-02-01  239   * the correct byte order, and be dword aligned. The input is a Xilinx .bin
b496df86ac1bbe Jason Gunthorpe    2017-02-01  240   * file with every 32 bit quantity swapped.
b496df86ac1bbe Jason Gunthorpe    2017-02-01  241   */
ada14a023a6411 Nava kishore Manne 2022-04-21  242  static bool zynq_fpga_has_sync(const char *buf, size_t count)
b496df86ac1bbe Jason Gunthorpe    2017-02-01  243  {
b496df86ac1bbe Jason Gunthorpe    2017-02-01  244  	for (; count >= 4; buf += 4, count -= 4)
b496df86ac1bbe Jason Gunthorpe    2017-02-01 @245  		if (buf[0] == 0x66 && buf[1] == 0x55 && buf[2] == 0x99 &&
b496df86ac1bbe Jason Gunthorpe    2017-02-01  246  		    buf[3] == 0xaa)
b496df86ac1bbe Jason Gunthorpe    2017-02-01  247  			return true;
b496df86ac1bbe Jason Gunthorpe    2017-02-01  248  	return false;
b496df86ac1bbe Jason Gunthorpe    2017-02-01  249  }
b496df86ac1bbe Jason Gunthorpe    2017-02-01  250  

:::::: The code at line 245 was first introduced by commit
:::::: b496df86ac1bbe393a55ddbfed35d46e74ef9767 fpga zynq: Check the bitstream for validity

:::::: TO: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
:::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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