Re: [PATCH] erofs: fix to avoid infinite loop in z_erofs_do_read_page() when read page beyond EOF

[Gao Xiang]

On 2023/7/10 17:34, Chunhai Guo wrote:

z_erofs_do_read_page() may loop infinitely due to the inappropriate
truncation in the below statement. Since the offset is 64 bits and min_t()
truncates the result to 32 bits. The solution is to replace unsigned int
with a 64-bit type, such as erofs_off_t.
     cur = end - min_t(unsigned int, offset + end - map->m_la, end);

     - For example:
         - offset = 0x400160000
         - end = 0x370
         - map->m_la = 0x160370
         - offset + end - map->m_la = 0x400000000
         - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
     - Expected result:
         - cur = 0
     - Actual result:
         - cur = 0x370

Signed-off-by: Chunhai Guo <guochun...@vivo.com>

I'd like to update the subject line manually to:

"erofs: avoid infinite loop in z_erofs_do_read_page() when reading beyond EOF"

since the original one is too long...

Otherwise it looks good to me,

Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Reviewed-by: Gao Xiang <hsiang...@linux.alibaba.com>

Thanks,
Gao Xiang