In the Linux kernel, the following vulnerability has been resolved:

ext4: don't BUG if someone dirty pages without asking ext4 first

[un]pin_user_pages_remote is dirtying pages without properly warning
the file system in advance.  A related race was noted by Jan Kara in
2018[1]; however, more recently instead of it being a very hard-to-hit
race, it could be reliably triggered by process_vm_writev(2) which was
discovered by Syzbot[2].

This is technically a bug in mm/gup.c, but arguably ext4 is fragile in
that if some other kernel subsystem dirty pages without properly
notifying the file system using page_mkwrite(), ext4 will BUG, while
other file systems will not BUG (although data will still be lost).

So instead of crashing with a BUG, issue a warning (since there may be
potential data loss) and just mark the page as clean to avoid
unprivileged denial of service attacks until the problem can be
properly fixed.  More discussion and background can be found in the
thread starting at [2].

[1] https://lore.kernel.org/linux-mm/[email protected]
[2] https://lore.kernel.org/r/[email protected]

https://git.kernel.org/stable/c/0d3a6926f7e8be3c897fa46216ce13b119a9f56a

https://git.kernel.org/stable/c/330d0e44fc5a47c27df958ecdd4693a3cb1d8b81

https://git.kernel.org/stable/c/343117559ef41e992e326f7a92da1a8f254dfa8c

https://git.kernel.org/stable/c/5a016c053f426a73752c3b41b60b497b58694d48

https://git.kernel.org/stable/c/5db60e76edf5680ff1f3a7221036fc44b308f146

https://git.kernel.org/stable/c/677c9d30e8487bee6c8e3b034070319d98f6e203

https://git.kernel.org/stable/c/a0856764dc1276ad2dc7891288c2e9246bf11a37

https://git.kernel.org/stable/c/cc5095747edfb054ca2068d01af20be3fcc3634f

https://git.kernel.org/stable/c/d666dfaa571465a19f014534a214c255ea33f301