Date: Thu, 3 Oct 2019 07:17:26 +0000 (UTC) From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r353032 - stable/12/sys/kern Message-ID: <201910030717.x937HQXe086112@repo.freebsd.org>
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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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