git: acb45ac680f7 - stable/13 - linux(4): Prevent an endless loop.

The branch stable/13 has been updated by dchagin:

URL: https://cgit.FreeBSD.org/src/commit/?id=acb45ac680f70ce5083d2275a6f40a8c116205ba

commit acb45ac680f70ce5083d2275a6f40a8c116205ba
Author:     Dmitry Chagin <dchagin@FreeBSD.org>
AuthorDate: 2021-07-20 11:40:08 +0000
Commit:     Dmitry Chagin <dchagin@FreeBSD.org>
CommitDate: 2022-06-17 19:33:12 +0000

    linux(4): Prevent an endless loop.
    
    In the futex_atomic_op() the encoded_op is a user-supplied parameter.
    If the user specifies an incorrect value for this parameter paired with a valid
    *uaddr parameter the caller will go into the endless loop. To prevent this check
    futex_atomic_op() result and break the loop in case of ENOSYS.
    
    MFC after:              2 weeks
    
    (cherry picked from commit ef4251e271486227f577494b8cc48623772a74ab)
---
 sys/compat/linux/linux_futex.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c
index f69b13585022..a32542b16a8a 100644
--- a/sys/compat/linux/linux_futex.c
+++ b/sys/compat/linux/linux_futex.c
@@ -845,6 +845,8 @@ retry:
 		if (f2 != NULL)
 			futex_put(f2, NULL);
 		futex_put(f, NULL);
+		if (op_ret == -ENOSYS)
+			return (ENOSYS);
 		error = copyin(args->uaddr2, &val, sizeof(val));
 		if (error == 0)
 			goto retry;