Re: [PATCH] erofs: fix validation in z_erofs_do_map_blocks()

[Gao Xiang]

Hi Noboru,

On 2023/3/3 14:52, Noboru Asai wrote:

In case of reading fragment data, map->m_plen is invalid.

Fixes: c505feba4c0d ("erofs: validate the extent length for uncompressed 
pclusters")
Signed-off-by: Noboru Asai <a...@sijam.com>

Thanks for the report and patch!

I've already found this issue and I think it's actually
a misuse to Z_EROFS_VLE_CLUSTER_TYPE_PLAIN for fragment
pclusters in mkfs.erofs.

So I fixed in erofs-utils:
https://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs-utils.git/commit/?id=ef74e215647e0d602d5e24039acbcfb18e55e516

Since erofs-utils v1.6 is not released yet, so it won't impact
anything at all.

Thanks,
Gao Xiang

---
  fs/erofs/zmap.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 8bf6d30518b6..902b166a5a5e 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -572,7 +572,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
        }

if (m.headtype == Z_EROFS_VLE_CLUSTER_TYPE_PLAIN) {

-               if (map->m_llen > map->m_plen) {
+               if (!(map->m_flags & EROFS_MAP_FRAGMENT) && (map->m_llen > 
map->m_plen) {
                        DBG_BUGON(1);
                        err = -EFSCORRUPTED;
                        goto unmap_out;