From 164f7e586739d07eb56af6f6d66acebb11f315c8 Mon Sep 17 00:00:00 2001
From: Pan Bian <bianpan2016@163.com>
Date: Fri, 30 Nov 2018 14:10:54 -0800
Subject: [PATCH] ocfs2: fix potential use after free
Git-commit: 164f7e586739d07eb56af6f6d66acebb11f315c8
Patch-mainline: v4.20-rc5
References: git-fixes
ocfs2_get_dentry() calls iput(inode) to drop the reference count of
inode, and if the reference count hits 0, inode is freed. However, in
this function, it then reads inode->i_generation, which may result in a
use after free bug. Move the put operation later.
Link: http://lkml.kernel.org/r/1543109237-110227-1-git-send-email-bianpan2016@163.com
Fixes: 781f200cb7a("ocfs2: Remove masklog ML_EXPORT.")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>
---
fs/ocfs2/export.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ocfs2/export.c b/fs/ocfs2/export.c
index 9f88188060db..4bf8d5854b27 100644
--- a/fs/ocfs2/export.c
+++ b/fs/ocfs2/export.c
@@ -125,10 +125,10 @@ static struct dentry *ocfs2_get_dentry(struct super_block *sb,
check_gen:
if (handle->ih_generation != inode->i_generation) {
- iput(inode);
trace_ocfs2_get_dentry_generation((unsigned long long)blkno,
handle->ih_generation,
inode->i_generation);
+ iput(inode);
result = ERR_PTR(-ESTALE);
goto bail;
}
--
2.35.3