Re: [PATCH] f2fs: use iostat_lat_type directly as a parameter in the iostat_update_and_unbind_ctx()

[Dan Carpenter]

Hi Yangtao,

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Yangtao-Li/f2fs-use-iostat_lat_type-directly-as-a-parameter-in-the-iostat_update_and_unbind_ctx/20230105-122414
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev-test
patch link:    https://lore.kernel.org/r/20230105042240.24738-1-frank.li%40vivo.com
patch subject: [PATCH] f2fs: use iostat_lat_type directly as a parameter in the iostat_update_and_unbind_ctx()
config: alpha-randconfig-m041-20230110
compiler: alpha-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>

New smatch warnings:
fs/f2fs/iostat.c:228 __update_iostat_latency() error: buffer overflow 'io_lat->sum_lat[type]' 3 <= 3
fs/f2fs/iostat.c:229 __update_iostat_latency() error: buffer overflow 'io_lat->bio_cnt[type]' 3 <= 3
fs/f2fs/iostat.c:230 __update_iostat_latency() error: buffer overflow 'io_lat->peak_lat[type]' 3 <= 3

Old smatch warnings:
fs/f2fs/iostat.c:231 __update_iostat_latency() error: buffer overflow 'io_lat->peak_lat[type]' 3 <= 3

vim +228 fs/f2fs/iostat.c

a4b6817625e71d Daeho Jeong 2021-08-20  211  static inline void __update_iostat_latency(struct bio_iostat_ctx *iostat_ctx,
2804a18e00dbd6 Yangtao Li  2023-01-05  212  				enum iostat_lat_type type)
a4b6817625e71d Daeho Jeong 2021-08-20  213  {
a4b6817625e71d Daeho Jeong 2021-08-20  214  	unsigned long ts_diff;
2804a18e00dbd6 Yangtao Li  2023-01-05  215  	unsigned int page_type = iostat_ctx->type;
a4b6817625e71d Daeho Jeong 2021-08-20  216  	struct f2fs_sb_info *sbi = iostat_ctx->sbi;
a4b6817625e71d Daeho Jeong 2021-08-20  217  	struct iostat_lat_info *io_lat = sbi->iostat_io_lat;
61803e984307c7 Daeho Jeong 2022-06-10  218  	unsigned long flags;
a4b6817625e71d Daeho Jeong 2021-08-20  219  
a4b6817625e71d Daeho Jeong 2021-08-20  220  	if (!sbi->iostat_enable)
a4b6817625e71d Daeho Jeong 2021-08-20  221  		return;
a4b6817625e71d Daeho Jeong 2021-08-20  222  
a4b6817625e71d Daeho Jeong 2021-08-20  223  	ts_diff = jiffies - iostat_ctx->submit_ts;
2804a18e00dbd6 Yangtao Li  2023-01-05  224  	if (page_type >= META_FLUSH)
                                                                 ^^^^^^^^^^

2804a18e00dbd6 Yangtao Li  2023-01-05  225  		page_type = META;
a4b6817625e71d Daeho Jeong 2021-08-20  226  
61803e984307c7 Daeho Jeong 2022-06-10  227  	spin_lock_irqsave(&sbi->iostat_lat_lock, flags);
2804a18e00dbd6 Yangtao Li  2023-01-05 @228  	io_lat->sum_lat[type][page_type] += ts_diff;
                                                                      ^^^^^^^^^
Mixup between META_FLUSH and NR_PAGE_TYPE leads to memory corruption.

2804a18e00dbd6 Yangtao Li  2023-01-05 @229  	io_lat->bio_cnt[type][page_type]++;
2804a18e00dbd6 Yangtao Li  2023-01-05 @230  	if (ts_diff > io_lat->peak_lat[type][page_type])
2804a18e00dbd6 Yangtao Li  2023-01-05  231  		io_lat->peak_lat[type][page_type] = ts_diff;
61803e984307c7 Daeho Jeong 2022-06-10  232  	spin_unlock_irqrestore(&sbi->iostat_lat_lock, flags);
a4b6817625e71d Daeho Jeong 2021-08-20  233  }

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