From c99493ce409c3b98fec1616dbcf24c102e006deb Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Mon, 20 Apr 2026 11:46:12 +0800 Subject: [PATCH] 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: 386292919c25 ("erofs: introduce readmore decompression strategy") Fixes: 307210c262a2 ("erofs: verify metadata accesses for file-backed mounts") Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- fs/erofs/data.c | 2 +- fs/erofs/zdata.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/erofs/data.c b/fs/erofs/data.c index 132a27deb2f3..b2c12c5856ac 100644 --- a/fs/erofs/data.c +++ b/fs/erofs/data.c @@ -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); diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 8a0b15511931..43bb5a6a9924 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -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; } }