svn commit: r353032 - stable/12/sys/kern
Andrew Turner
andrew at FreeBSD.org
Thu Oct 3 07:17:27 UTC 2019
Author: andrew
Date: Thu Oct 3 07:17:26 2019
New Revision: 353032
URL: https://svnweb.freebsd.org/changeset/base/353032
Log:
MFC r352796:
Check the vfs option length is valid before accessing through
When a VFS option passed to nmount is present but NULL the kernel will
place an empty option in its internal list. This will have a NULL
pointer and a length of 0. When we come to read one of these the kernel
will try to load from the last address of virtual memory. This is
normally invalid so will fault resulting in a kernel panic.
Fix this by checking if the length is valid before dereferencing.
Sponsored by: DARPA, AFRL
Modified:
stable/12/sys/kern/vfs_mount.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/kern/vfs_mount.c
==============================================================================
--- stable/12/sys/kern/vfs_mount.c Thu Oct 3 06:08:04 2019 (r353031)
+++ stable/12/sys/kern/vfs_mount.c Thu Oct 3 07:17:26 2019 (r353032)
@@ -603,7 +603,7 @@ vfs_donmount(struct thread *td, uint64_t fsflags, stru
*/
fstypelen = 0;
error = vfs_getopt(optlist, "fstype", (void **)&fstype, &fstypelen);
- if (error || fstype[fstypelen - 1] != '\0') {
+ if (error || fstypelen <= 0 || fstype[fstypelen - 1] != '\0') {
error = EINVAL;
if (errmsg != NULL)
strncpy(errmsg, "Invalid fstype", errmsg_len);
@@ -611,7 +611,7 @@ vfs_donmount(struct thread *td, uint64_t fsflags, stru
}
fspathlen = 0;
error = vfs_getopt(optlist, "fspath", (void **)&fspath, &fspathlen);
- if (error || fspath[fspathlen - 1] != '\0') {
+ if (error || fspathlen <= 0 || fspath[fspathlen - 1] != '\0') {
error = EINVAL;
if (errmsg != NULL)
strncpy(errmsg, "Invalid fspath", errmsg_len);
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