[PATCH AUTOSEL 4.9 14/28] jffs2: fix use-after-free on symlink traversal
From: Sasha Levin <sashal@kernel.org>
Date: 2019-04-24 14:50:54
Also in:
lkml
Subsystem:
filesystems (vfs and infrastructure), journalling flash file system v2 (jffs2), the rest · Maintainers:
Alexander Viro, Christian Brauner, David Woodhouse, Richard Weinberger, Linus Torvalds
From: Al Viro <viro@zeniv.linux.org.uk> [ Upstream commit 4fdcfab5b5537c21891e22e65996d4d0dd8ab4ca ] free the symlink body after the same RCU delay we have for freeing the struct inode itself, so that traversal during RCU pathwalk wouldn't step into freed memory. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/jffs2/readinode.c | 5 ----- fs/jffs2/super.c | 5 ++++- 2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index 06a71dbd4833..2f236cca6095 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c@@ -1414,11 +1414,6 @@ void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f) jffs2_kill_fragtree(&f->fragtree, deleted?c:NULL); - if (f->target) { - kfree(f->target); - f->target = NULL; - } - fds = f->dents; while(fds) { fd = fds;
diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index 226640563df3..76aedbc97773 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c@@ -47,7 +47,10 @@ static struct inode *jffs2_alloc_inode(struct super_block *sb) static void jffs2_i_callback(struct rcu_head *head) { struct inode *inode = container_of(head, struct inode, i_rcu); - kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode)); + struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode); + + kfree(f->target); + kmem_cache_free(jffs2_inode_cachep, f); } static void jffs2_destroy_inode(struct inode *inode)
--
2.19.1