Date: Mon, 30 May 2022 14:05:33 -0400 From: Mark Johnston <markj@freebsd.org> To: Kirk McKusick <mckusick@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 076002f24d35 - main - Do comprehensive UFS/FFS superblock integrity checks when reading a superblock. Message-ID: <YpUHbQvHGiL0SdcX@nuc> In-Reply-To: <202205271922.24RJMOJ2039923@gitrepo.freebsd.org> References: <202205271922.24RJMOJ2039923@gitrepo.freebsd.org>
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On Fri, May 27, 2022 at 07:22:24PM +0000, Kirk McKusick wrote: > The branch main has been updated by mckusick: > > URL: https://cgit.FreeBSD.org/src/commit/?id=076002f24d35962f0d21f44bfddd34ee4d7f015d > > commit 076002f24d35962f0d21f44bfddd34ee4d7f015d > Author: Kirk McKusick <mckusick@FreeBSD.org> > AuthorDate: 2022-05-27 19:21:11 +0000 > Commit: Kirk McKusick <mckusick@FreeBSD.org> > CommitDate: 2022-05-27 19:22:07 +0000 > > Do comprehensive UFS/FFS superblock integrity checks when reading a superblock. > > Historically only minimal checks were made of a superblock when it > was read in as it was assumed that fsck would have been run to > correct any errors before attempting to use the filesystem. Recently > several bug reports have been submitted reporting kernel panics > that can be triggered by deliberately corrupting filesystem superblocks, > see Bug 263979 - [meta] UFS / FFS / GEOM crash (panic) tracking > which is tracking the reported corruption bugs. > > This change upgrades the checks that are performed. These additional > checks should prevent panics from a corrupted superblock. Although > it appears in only one place, the new code will apply to the kernel > modules and (through libufs) user applications that read in superblocks. > > Reported by: Robert Morris and Neeraj > Reviewed by: kib > Tested by: Peter Holm > PR: 263979 > MFC after: 1 month > Differential Revision: https://reviews.freebsd.org/D35219 > --- > sys/ufs/ffs/ffs_subr.c | 163 +++++++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 146 insertions(+), 17 deletions(-) > > diff --git a/sys/ufs/ffs/ffs_subr.c b/sys/ufs/ffs/ffs_subr.c > index 01e9f45e1205..28c2fee1cb37 100644 > --- a/sys/ufs/ffs/ffs_subr.c > +++ b/sys/ufs/ffs/ffs_subr.c > [...] > +static int > +validate_sblock(struct fs *fs, int isaltsblk) > +{ > + int i, sectorsize; > + u_int64_t maxfilesize, minfpg, sizepb; > + > + sectorsize = dbtob(1); > + if (fs->fs_magic == FS_UFS2_MAGIC) { > + if ((!isaltsblk && (fs->fs_sblockloc != SBLOCK_UFS2 || > + fs->fs_sblockactualloc != SBLOCK_UFS2)) || > + fs->fs_maxsymlinklen != ((UFS_NDADDR + UFS_NIADDR) * > + sizeof(ufs2_daddr_t)) || > + fs->fs_nindir != fs->fs_bsize / sizeof(ufs2_daddr_t) || > + fs->fs_inopb != fs->fs_bsize / sizeof(struct ufs2_dinode)) > + return (ENOENT); > + } else if (fs->fs_magic == FS_UFS1_MAGIC) { > + if ((!isaltsblk && (fs->fs_sblockloc > SBLOCK_UFS1 || > + fs->fs_sblockactualloc != SBLOCK_UFS1)) || Hi Kirk, The tests of fs_sblockactualloc fail on older filesystems or those created by makefs(8), causing mount to fail. That field was added relatively recently, so I suspect a value of zero should also be permitted?
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