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| author | Eric Biggers <ebiggers@google.com> | 2018-01-31 00:49:18 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-16 20:07:00 +0100 |
| commit | 4d5d5e9612e7af09bb218d0dd2455873b6faca77 (patch) | |
| tree | 69ffe4e86d45fc007a9f10ec3cf9caac9e419dd7 | |
| parent | 8ec68ce24fd19bebabed20e3812d1befbd4be4d4 (diff) | |
| download | linux-stable-4d5d5e9612e7af09bb218d0dd2455873b6faca77.tar.gz linux-stable-4d5d5e9612e7af09bb218d0dd2455873b6faca77.tar.bz2 linux-stable-4d5d5e9612e7af09bb218d0dd2455873b6faca77.zip | |
devpts: fix error handling in devpts_mntget()
commit c9cc8d01fb04117928830449388512a5047569c9 upstream.
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>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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; } |