| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.18 002/105] hfsplus: dont return 0 when fill_super() failed | Date | Mon, 24 Sep 2018 13:32:48 +0200 |
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3.18-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
[ Upstream commit 7464726cb5998846306ed0a7d6714afb2e37b25d ]
syzbot is reporting NULL pointer dereference at mount_fs() [1]. This is because hfsplus_fill_super() is by error returning 0 when hfsplus_fill_super() detected invalid filesystem image, and mount_bdev() is returning NULL because dget(s->s_root) == NULL if s->s_root == NULL, and mount_fs() is accessing root->d_sb because IS_ERR(root) == false if root == NULL. Fix this by returning -EINVAL when hfsplus_fill_super() detected invalid filesystem image.
[1] https://syzkaller.appspot.com/bug?id=21acb6850cecbc960c927229e597158cf35f33d0
Link: http://lkml.kernel.org/r/d83ce31a-874c-dd5b-f790-41405983a5be@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+01ffaf5d9568dd1609f7@syzkaller.appspotmail.com> Reviewed-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/hfsplus/super.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/fs/hfsplus/super.c +++ b/fs/hfsplus/super.c @@ -518,8 +518,10 @@ static int hfsplus_fill_super(struct sup hfsplus_cat_build_key(sb, fd.search_key, HFSPLUS_ROOT_CNID, &str); if (!hfs_brec_read(&fd, &entry, sizeof(entry))) { hfs_find_exit(&fd); - if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) + if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) { + err = -EINVAL; goto out_put_root; + } inode = hfsplus_iget(sb, be32_to_cpu(entry.folder.id)); if (IS_ERR(inode)) { err = PTR_ERR(inode);
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