Re: [PATCH v3 1/2] f2fs: fix to avoid potential memory corruption in __update_iostat_latency()

[Chao Yu]

On 2023/1/21 0:16, Yangtao Li wrote:
> Add iotype sanity check to avoid potential memory corruption.
> This is to fix the compile error below:
>
> fs/f2fs/iostat.c:231 __update_iostat_latency() error: buffer overflow
> 'io_lat->peak_lat[type]' 3 <= 3
>
> vim +228 fs/f2fs/iostat.c
>
>    211  static inline void __update_iostat_latency(struct bio_iostat_ctx
> 	*iostat_ctx,
>    212					enum iostat_lat_type type)
>    213  {
>    214		unsigned long ts_diff;
>    215		unsigned int page_type = iostat_ctx->type;
>    216		struct f2fs_sb_info *sbi = iostat_ctx->sbi;
>    217		struct iostat_lat_info *io_lat = sbi->iostat_io_lat;
>    218		unsigned long flags;
>    219
>    220		if (!sbi->iostat_enable)
>    221			return;
>    222
>    223		ts_diff = jiffies - iostat_ctx->submit_ts;
>    224		if (page_type >= META_FLUSH)
>                                   ^^^^^^^^^^
>
>    225			page_type = META;
>    226
>    227		spin_lock_irqsave(&sbi->iostat_lat_lock, flags);
>   @228		io_lat->sum_lat[type][page_type] += ts_diff;
>                                        ^^^^^^^^^
> Mixup between META_FLUSH and NR_PAGE_TYPE leads to memory corruption.
>
> Fixes: a4b6817625e7 ("f2fs: introduce periodic iostat io latency traces")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> Suggested-by: Chao Yu <chao@xxxxxxxxxx>
> Suggested-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,