Date: Fri, 28 Oct 2016 11:34:32 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r308024 - head/sys/fs/msdosfs Message-ID: <201610281134.u9SBYWjh004570@repo.freebsd.org>
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Author: kib Date: Fri Oct 28 11:34:32 2016 New Revision: 308024 URL: https://svnweb.freebsd.org/changeset/base/308024 Log: Ensure that cluster allocations never allocate clusters outside the volume limits. In particular: - Assert that usemap_alloc() and usemap_free() cluster number argument is valid. - In chainlength(), return 0 if cluster start is after the max cluster. - In chainlength(), cut the calculated cluster chain length at the max cluster. - For true paranoia, after the pm_inusemap is calculated in fillinusemap(), reset all bits in the array for clusters after the max cluster, as in-use. Reported and tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Modified: head/sys/fs/msdosfs/msdosfs_fat.c Modified: head/sys/fs/msdosfs/msdosfs_fat.c ============================================================================== --- head/sys/fs/msdosfs/msdosfs_fat.c Fri Oct 28 11:26:44 2016 (r308023) +++ head/sys/fs/msdosfs/msdosfs_fat.c Fri Oct 28 11:34:32 2016 (r308024) @@ -382,6 +382,8 @@ usemap_alloc(struct msdosfsmount *pmp, u MSDOSFS_ASSERT_MP_LOCKED(pmp); + KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, + pmp->pm_maxcluster)); KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, ("usemap_alloc on ro msdosfs mount")); KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) @@ -398,6 +400,9 @@ usemap_free(struct msdosfsmount *pmp, u_ { MSDOSFS_ASSERT_MP_LOCKED(pmp); + + KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, + pmp->pm_maxcluster)); KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, ("usemap_free on ro msdosfs mount")); pmp->pm_freeclustercount++; @@ -637,6 +642,8 @@ chainlength(struct msdosfsmount *pmp, u_ MSDOSFS_ASSERT_MP_LOCKED(pmp); + if (start > pmp->pm_maxcluster) + return (0); max_idx = pmp->pm_maxcluster / N_INUSEBITS; idx = start / N_INUSEBITS; start %= N_INUSEBITS; @@ -644,11 +651,18 @@ chainlength(struct msdosfsmount *pmp, u_ map &= ~((1 << start) - 1); if (map) { len = ffs(map) - 1 - start; - return (len > count ? count : len); + len = MIN(len, count); + if (start + len > pmp->pm_maxcluster) + len = pmp->pm_maxcluster - start + 1; + return (len); } len = N_INUSEBITS - start; - if (len >= count) - return (count); + if (len >= count) { + len = count; + if (start + len > pmp->pm_maxcluster) + len = pmp->pm_maxcluster - start + 1; + return (len); + } while (++idx <= max_idx) { if (len >= count) break; @@ -659,7 +673,10 @@ chainlength(struct msdosfsmount *pmp, u_ } len += N_INUSEBITS; } - return (len > count ? count : len); + len = MIN(len, count); + if (start + len > pmp->pm_maxcluster) + len = pmp->pm_maxcluster - start + 1; + return (len); } /* @@ -918,6 +935,11 @@ fillinusemap(struct msdosfsmount *pmp) } if (bp != NULL) brelse(bp); + + for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + + N_INUSEBITS) / N_INUSEBITS; cn++) + pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); + return (0); }
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