This is a note to let you know that I've just added the patch titled
nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7ee29facd8a9c5a26079148e36bcf07141b3a6bc Mon Sep 17 00:00:00 2001
From: Pan Bian <bianpan2016@xxxxxxx>
Date: Thu, 21 Sep 2023 23:17:31 +0900
Subject: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()
From: Pan Bian <bianpan2016@xxxxxxx>
commit 7ee29facd8a9c5a26079148e36bcf07141b3a6bc upstream.
In nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the
reference count of bh when the call to nilfs_dat_translate() fails. If
the reference count hits 0 and its owner page gets unlocked, bh may be
freed. However, bh->b_page is dereferenced to put the page after that,
which may result in a use-after-free bug. This patch moves the release
operation after unlocking and putting the page.
NOTE: The function in question is only called in GC, and in combination
with current userland tools, address translation using DAT does not occur
in that function, so the code path that causes this issue will not be
executed. However, it is possible to run that code path by intentionally
modifying the userland GC library or by calling the GC ioctl directly.
[konishi.ryusuke@xxxxxxxxx: NOTE added to the commit log]
Link: https://lkml.kernel.org/r/1543201709-53191-1-git-send-email-bianpan2016@xxxxxxx
Link: https://lkml.kernel.org/r/20230921141731.10073-1-konishi.ryusuke@xxxxxxxxx
Fixes: a3d93f709e89 ("nilfs2: block cache for garbage collection")
Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
Reported-by: Ferry Meng <mengferry@xxxxxxxxxxxxxxxxx>
Closes: https://lkml.kernel.org/r/20230818092022.111054-1-mengferry@xxxxxxxxxxxxxxxxx
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/gcinode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/nilfs2/gcinode.c
+++ b/fs/nilfs2/gcinode.c
@@ -82,10 +82,8 @@ int nilfs_gccache_submit_read_data(struc
struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
- if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
- brelse(bh);
+ if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
goto failed;
- }
}
lock_buffer(bh);
@@ -111,6 +109,8 @@ int nilfs_gccache_submit_read_data(struc
failed:
unlock_page(bh->b_page);
put_page(bh->b_page);
+ if (unlikely(err))
+ brelse(bh);
return err;
}
Patches currently in stable-queue which might be from bianpan2016@xxxxxxx are
queue-4.14/nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data.patch
