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erofs: fix offset truncation when shifting pgoff on 32-bit platforms 

On 32-bit platforms, pgoff_t is 32 bits wide, so left-shifting
large arbitrary pgoff_t values by PAGE_SHIFT performs 32-bit arithmetic
and silently truncates the result for pages beyond the 4 GiB boundary.

Cast the page index to loff_t before shifting to produce a correct
64-bit byte offset.

Fixes: 386292919c ("erofs: introduce readmore decompression strategy")
Fixes: 307210c262 ("erofs: verify metadata accesses for file-backed mounts")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Gao Xiang 2026-04-20 11:46:12 +08:00
parent d18a3b5d33
commit c99493ce40
2 changed files with 2 additions and 2 deletions
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2
fs/erofs/data.c
View File

@ -39,7 +39,7 @@ void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset, bool need_kmap)
* However, the data access range must be verified here in advance.
*/
if (buf->file) {
fpos = index << PAGE_SHIFT;
fpos = (loff_t)index << PAGE_SHIFT;
err = rw_verify_area(READ, buf->file, &fpos, PAGE_SIZE);
if (err < 0)
return ERR_PTR(err);

2
fs/erofs/zdata.c
View File

@ -1872,7 +1872,7 @@ static void z_erofs_pcluster_readmore(struct z_erofs_frontend *f,
if (cur < PAGE_SIZE)
break;
cur = (index << PAGE_SHIFT) - 1;
cur = ((loff_t)index << PAGE_SHIFT) - 1;
}
}