mtd is getting NULL dereferenced in jffs2_parse_param(), while checking condition for pool size when, case: opt is Opt_rp_size hits.
- fs/jffs2/super.c The bug seems to get triggered in this line: if (opt > c->mtd->size) return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB", c->mtd->size / 1024); Fix this by adding a NULL check for 'c->mtd' device and return invalf(); which wraps errorf() and returns -EINVAL for convenience, which allows userspace to collect them directly. Reported-and-tested-by: syzbot+9765367bb86a19d38...@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=9765367bb86a19d38732 Signed-off-by: Anmol Karn <anmol.karan...@gmail.com> --- fs/jffs2/super.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c index 05d7878dfad1..f4ce67ac8486 100644 --- a/fs/jffs2/super.c +++ b/fs/jffs2/super.c @@ -203,6 +203,10 @@ static int jffs2_parse_param(struct fs_context *fc, struct fs_parameter *param) if (result.uint_32 > UINT_MAX / 1024) return invalf(fc, "jffs2: rp_size unrepresentable"); opt = result.uint_32 * 1024; + + if (!c->mtd) + return invalf(fc, "jffs2: mtd device is NULL"); + if (opt > c->mtd->size) return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB", c->mtd->size / 1024); -- 2.28.0