[src/trunk]: src/sys/sys Fix stupid bugs in linux_sys_shmctl(): the index cou...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f4fa099be080
branches:  trunk
changeset: 1002983:f4fa099be080
user:      maxv <maxv%NetBSD.org@localhost>
date:      Fri Aug 23 10:22:14 2019 +0000

description:
Fix stupid bugs in linux_sys_shmctl(): the index could be out of bound
(page fault) and there was no proper locking.

Maybe we should just remove LINUX_SHM_STAT, like compat_linux32.

diffstat:

 sys/compat/linux/common/linux_ipc.c |  10 +++++++---
 sys/kern/sysv_shm.c                 |  24 ++++++++++++++++++++++--
 sys/sys/shm.h                       |   4 +++-
 3 files changed, 32 insertions(+), 6 deletions(-)

diffs (101 lines):

diff -r 1db329bf25ea -r f4fa099be080 sys/compat/linux/common/linux_ipc.c
--- a/sys/compat/linux/common/linux_ipc.c       Fri Aug 23 09:41:26 2019 +0000
+++ b/sys/compat/linux/common/linux_ipc.c       Fri Aug 23 10:22:14 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_ipc.c,v 1.56 2019/02/21 03:37:18 mrg Exp $       */
+/*     $NetBSD: linux_ipc.c,v 1.57 2019/08/23 10:22:15 maxv Exp $      */
 
 /*-
  * Copyright (c) 1995, 1998 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_ipc.c,v 1.56 2019/02/21 03:37:18 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_ipc.c,v 1.57 2019/08/23 10:22:15 maxv Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_sysv.h"
@@ -568,6 +568,7 @@
                syscallarg(struct linux_shmid_ds *) buf;
        } */
        struct shmid_ds bs;
+       struct ipc_perm perm;
        struct linux_shmid_ds ls;
        struct linux_shmid64_ds ls64;
        struct linux_shminfo64 lsi64;
@@ -582,7 +583,10 @@
 
        switch (cmd & ~LINUX_IPC_64) {
        case LINUX_SHM_STAT:
-               shmid = IXSEQ_TO_IPCID(shmid, shmsegs[shmid].shm_perm);
+               error = shm_find_segment_perm_by_index(shmid, &perm);
+               if (error)
+                       return error;
+               shmid = IXSEQ_TO_IPCID(shmid, perm);
                retval[0] = shmid;
                /*FALLTHROUGH*/
 
diff -r 1db329bf25ea -r f4fa099be080 sys/kern/sysv_shm.c
--- a/sys/kern/sysv_shm.c       Fri Aug 23 09:41:26 2019 +0000
+++ b/sys/kern/sysv_shm.c       Fri Aug 23 10:22:14 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sysv_shm.c,v 1.137 2019/08/07 00:38:02 pgoyette Exp $  */
+/*     $NetBSD: sysv_shm.c,v 1.138 2019/08/23 10:22:14 maxv Exp $      */
 
 /*-
  * Copyright (c) 1999, 2007 The NetBSD Foundation, Inc.
@@ -61,7 +61,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sysv_shm.c,v 1.137 2019/08/07 00:38:02 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sysv_shm.c,v 1.138 2019/08/23 10:22:14 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_sysv.h"
@@ -121,6 +121,26 @@
 static int shmrealloc(int);
 
 /*
+ * Find the shared memory segment permission by the index. Only used by
+ * compat_linux to implement SHM_STAT.
+ */
+int
+shm_find_segment_perm_by_index(int index, struct ipc_perm *perm)
+{
+       struct shmid_ds *shmseg;
+
+       mutex_enter(&shm_lock);
+       if (index < 0 || index >= shminfo.shmmni) {
+               mutex_exit(&shm_lock);
+               return EINVAL;
+       }
+       shmseg = &shmsegs[index];
+       memcpy(perm, &shmseg->shm_perm, sizeof(*perm));
+       mutex_exit(&shm_lock);
+       return 0;
+}
+
+/*
  * Find the shared memory segment by the identifier.
  *  => must be called with shm_lock held;
  */
diff -r 1db329bf25ea -r f4fa099be080 sys/sys/shm.h
--- a/sys/sys/shm.h     Fri Aug 23 09:41:26 2019 +0000
+++ b/sys/sys/shm.h     Fri Aug 23 10:22:14 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: shm.h,v 1.53 2019/08/07 00:38:02 pgoyette Exp $        */
+/*     $NetBSD: shm.h,v 1.54 2019/08/23 10:22:14 maxv Exp $    */
 
 /*-
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -178,6 +178,8 @@
 void   shmexit(struct vmspace *);
 int    shmctl1(struct lwp *, int, int, struct shmid_ds *);
 
+int    shm_find_segment_perm_by_index(int, struct ipc_perm *);
+
 extern void (*uvm_shmexit)(struct vmspace *);
 extern void (*uvm_shmfork)(struct vmspace *, struct vmspace *);