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

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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 <guochunhai@vivo.com>
Fixes: 3883a79abd ("staging: erofs: introduce VLE decompression support")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230710093410.44071-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
(cherry picked from commit 8191213a5835b0317c5e4d0d337ae1ae00c75253
    https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git dev)
Bug: 296824280

Change-Id: I152508ba4c0eb83aeae5d753e22b0ca8d3ada56d
Signed-off-by: sunshijie <sunshijie@xiaomi.corp-partner.google.com>
Signed-off-by: sunshijie <sunshijie@xiaomi.com>
This commit is contained in:
sunshijie 2023-08-21 21:02:05 +08:00 committed by Sandeep Dhavale
parent 8497f46a87
commit ffaab71302
1 changed files with 1 additions and 1 deletions
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2
fs/erofs/zdata.c
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@ -855,7 +855,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
*/
tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
cur = end - min_t(unsigned int, offset + end - map->m_la, end);
cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
if (!(map->m_flags & EROFS_MAP_MAPPED)) {
zero_user_segment(page, cur, end);
goto next_part;