[BUG] bfs: WARNING in mark_buffer_dirty from bfs_get_block

[CJ]

Hi,


I am reporting that WARNING in mark_buffer_dirty remains reproducible with a
migrated syzkaller reproducer on Linux 7.2-rc3. The tested HEAD commit is
a13c140cc289c0b7b3770bce5b3ad42ab35074aa.


The reproducer writes to a file on a crafted BFS filesystem and enters
bfs_get_block() through the buffered write path.


bfs_get_block() reaches mark_buffer_dirty(), which warns about the state of
the metadata buffer while servicing the write.


This looks like BFS marks a metadata buffer dirty before its state has been
validated or initialized correctly for the malformed filesystem image.


This issue was previously reported at:


https://syzkaller.appspot.com/bug?extid=5b2e10c67416270b15c0


Reproducer:


syz reproducer: https://pastebin.com/raw/VUbaJzLB


console output: https://pastebin.com/raw/sFnagzbT
kernel config: https://pastebin.com/raw/B0f3dC7H


Kernel:


HEAD commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
git tree: torvalds/linux
kernel version: 7.2.0-rc3 #1 PREEMPT(full)
tested tag: v7.2-rc3


Let me know if you need more details or testing.


Best regards