romfs: detect hard link cycles

romfs_iget() follows on-disk hard link entries until it reaches a non-hard
link inode:

	pos = be32_to_cpu(ri.spec) & ROMFH_MASK;

The target position is image-controlled, and the loop does not detect
cycles. A crafted romfs image can make the root inode a hard link. The hard
link can point back to itself and leave mount(2) spinning in the kernel.

Reject excessive hard link indirection with -ELOOP. Normal romfs images do
not need long hard link chains. This bounds corrupted-image traversal.
Propagate romfs_iget() errors from lookup because hard link traversal can
now fail with -ELOOP.

Signed-off-by: 이상호 <kudo3228@gmail.com>
Link: https://patch.msgid.link/20260701220729.822112-1-kudo3228@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions