diff options
| author | Eric Biggers <ebiggers@google.com> | 2018-01-31 00:49:18 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-31 08:48:37 -0800 |
| commit | c9cc8d01fb04117928830449388512a5047569c9 (patch) | |
| tree | b7e97b68733d1ee57025aed05373041d5912853f | |
| parent | c0cef30e4ff0dc025f4a1660b8f0ba43ed58426e (diff) | |
devpts: fix error handling in devpts_mntget()
If devpts_ptmx_path() returns an error code, then devpts_mntget()
dereferences an ERR_PTR():
BUG: unable to handle kernel paging request at fffffffffffffff5
IP: devpts_mntget+0x13f/0x280 fs/devpts/inode.c:173
Fix it by returning early in the error paths.
Reproducer:
#define _GNU_SOURCE
#include <fcntl.h>
#include <sched.h>
#include <sys/ioctl.h>
#define TIOCGPTPEER _IO('T', 0x41)
int main()
{
for (;;) {
int fd = open("/dev/ptmx", 0);
unshare(CLONE_NEWNS);
ioctl(fd, TIOCGPTPEER, 0);
}
}
Fixes: 311fc65c9fb9 ("pty: Repair TIOCGPTPEER")
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org> # v4.13+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/devpts/inode.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 7eae33ffa3fc..e31d6ed3ec32 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -168,11 +168,11 @@ struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) dput(path.dentry); if (err) { mntput(path.mnt); - path.mnt = ERR_PTR(err); + return ERR_PTR(err); } if (DEVPTS_SB(path.mnt->mnt_sb) != fsi) { mntput(path.mnt); - path.mnt = ERR_PTR(-ENODEV); + return ERR_PTR(-ENODEV); } return path.mnt; } |