Commit c99493ce authored by Gao Xiang's avatar Gao Xiang
Browse files

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: 38629291 ("erofs: introduce readmore decompression strategy")
Fixes: 307210c2 ("erofs: verify metadata accesses for file-backed mounts")
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent d18a3b5d

fs/erofs/data.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

fs/erofs/zdata.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

}