From 1b786d01917ccd90f4b2fffab8e735a25707e63d Mon Sep 17 00:00:00 2001 From: "Bjoern A. Zeeb" Date: Sat, 14 Mar 2020 14:04:55 +0000 Subject: [PATCH] kern_jail: missing \0 termination check on osrelease parameter If a user spplies a non-\0 terminated osrelease parameter reading it back may disclose kernel memory. This is a problem in case of nested jails (children.max > 0, which is not the default). Otherwise root outside the jail has access to kernel memory by other means and root inside a jail cannot create a child jail. Add the proper \0 check at the end of a supplied osrelease parameter and make sure any copies of the field will be \0-terminated. Submitted by: Hans Christian Woithe (chwoithe yahoo.com) MFC after: 3 days --- sys/kern/kern_jail.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index df4926248b28..09b8a0d5a7bb 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -865,8 +865,12 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags) "osrelease cannot be changed after creation"); goto done_errmsg; } - if (len == 0 || len >= OSRELEASELEN) { + if (len == 0 || osrelstr[len - 1] != '\0') { error = EINVAL; + goto done_free; + } + if (len >= OSRELEASELEN) { + error = ENAMETOOLONG; vfs_opterror(opts, "osrelease string must be 1-%d bytes long", OSRELEASELEN - 1); @@ -1241,9 +1245,11 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags) pr->pr_osreldate = osreldt ? osreldt : ppr->pr_osreldate; if (osrelstr == NULL) - strcpy(pr->pr_osrelease, ppr->pr_osrelease); + strlcpy(pr->pr_osrelease, ppr->pr_osrelease, + sizeof(pr->pr_osrelease)); else - strcpy(pr->pr_osrelease, osrelstr); + strlcpy(pr->pr_osrelease, osrelstr, + sizeof(pr->pr_osrelease)); LIST_INIT(&pr->pr_children); mtx_init(&pr->pr_mtx, "jail mutex", NULL, MTX_DEF | MTX_DUPOK);