[SRU][Jammy/Lunar][PATCH 0/1] CVE-2023-2898

[Yuxuan Luo]

[Impact]
There is a null-pointer-dereference flaw found in f2fs_write_end_io in
fs/f2fs/data.c in the Linux kernel. This flaw allows a local privileged
user to cause a denial of service problem.

[Backport]
It is a clean cherry pick for Lunar.
For Jammy, conflicts in `gc.c` requires e4544b63a7ee (“f2fs: move f2fs to use
reader-unfair rwsems”); however, since the part related to the fix
commit is merely renaming, it is possible to ignore this commit.

[Test]
Smoke tested on Lunar.

```bash
# apt-get install f2fs-tools -y
# modprobe f2fs
# modprobe null_blk gb=2 memory_backed=1 discard=1 # discard option is
						   # not available in Jammy
# mkdir /mnt/f2fs
# mkfs.f2fs -l label /dev/nullb0
# mount -t f2fs /dev/nullb0 /mnt/f2fs
# echo "hello" | sudo tee /mnt/f2fs/test
$ cat /mnt/f2fs/test
```

Compile and boot tested on Jammy.

[Potential Regression]
Expect low regression potential.

Chao Yu (1):
  f2fs: fix to avoid NULL pointer dereference f2fs_write_end_io()

 fs/f2fs/f2fs.h |  2 +-
 fs/f2fs/file.c |  2 +-
 fs/f2fs/gc.c   | 21 ++++++++++++++++++---
 3 files changed, 20 insertions(+), 5 deletions(-)

-- 
2.34.1