The patch titled
Subject: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Pan Bian <bianpan2016@xxxxxxx>
Subject: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data()
Date: Thu, 21 Sep 2023 23:17:31 +0900
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>
---
fs/nilfs2/gcinode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/nilfs2/gcinode.c~nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data
+++ a/fs/nilfs2/gcinode.c
@@ -73,10 +73,8 @@ 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);
@@ -102,6 +100,8 @@ 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 -mm which might be from bianpan2016@xxxxxxx are
nilfs2-fix-potential-use-after-free-in-nilfs_gccache_submit_read_data.patch
