[PATCH] ext4: do not BUG when INLINE_DATA_FL lacks system.data xattr

[Theodore Ts'o]

On Thu, Jul 10, 2025 at 01:01:04AM -0700, Moon Hee Lee wrote:
> From 4c910ac989e7a6d97565a67677a1ee88e2d1a9ad Mon Sep 17 00:00:00 2001
> From: Moon Hee Lee <moonhee.lee.ca@xxxxxxxxx>
> Date: Thu, 10 Jul 2025 00:36:59 -0700
> Subject: [PATCH] ext4: bail out when INLINE_DATA_FL lacks system.data xattr
> 
> A syzbot fuzzed image triggered a BUG_ON in ext4_update_inline_data()
> when an inode had the INLINE_DATA_FL flag set but was missing the
> system.data extended attribute.
> 
> ext4_prepare_inline_data() now checks for the presence of that xattr
> and returns -EFSCORRUPTED if it is missing, preventing corrupted inodes
> from reaching the update path and triggering a crash.

Thanks ofor the patch!  However, instead of doing an xattr lookup in
ext4_prepare_inline_data(), we can more simply and more efficiently
just not BUG in ext4_update_inline_data, like this: