Date: Fri, 26 Aug 2022 07:10:27 GMT From: Kirk McKusick <mckusick@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: f0be378a66a7 - main - Updates to UFS/FFS superblock integrity checks when reading a superblock. Message-ID: <202208260710.27Q7AR6t097391@gitrepo.freebsd.org>
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The branch main has been updated by mckusick: URL: https://cgit.FreeBSD.org/src/commit/?id=f0be378a66a75ebf335e9388ef0d319a70064d94 commit f0be378a66a75ebf335e9388ef0d319a70064d94 Author: Kirk McKusick <mckusick@FreeBSD.org> AuthorDate: 2022-08-26 07:09:01 +0000 Commit: Kirk McKusick <mckusick@FreeBSD.org> CommitDate: 2022-08-26 07:09:01 +0000 Updates to UFS/FFS superblock integrity checks when reading a superblock. Further updates based on ways Peter Holm found to corrupt UFS superblocks in ways that could cause kernel hangs or crashes. No legitimate superblocks should fail as a result of these changes. Reported by: Peter Holm Tested by: Peter Holm Sponsored by: The FreeBSD Foundation --- sys/ufs/ffs/ffs_subr.c | 70 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 53 insertions(+), 17 deletions(-) diff --git a/sys/ufs/ffs/ffs_subr.c b/sys/ufs/ffs/ffs_subr.c index 8c081313f873..f6c27cb38d62 100644 --- a/sys/ufs/ffs/ffs_subr.c +++ b/sys/ufs/ffs/ffs_subr.c @@ -333,6 +333,8 @@ readsuper(void *devfd, struct fs **fsp, off_t sblockloc, int flags, MPRINT("UFS%d superblock failed: %s (" #fmt ") %s %s (" \ #fmt ")\n", fs->fs_magic == FS_UFS1_MAGIC ? 1 : 2, \ #lhs, (intmax_t)lhs, #op, #rhs, (intmax_t)rhs); \ + if (error < 0) \ + return (ENOENT); \ if (error == 0) \ error = ENOENT; \ } @@ -351,6 +353,8 @@ readsuper(void *devfd, struct fs **fsp, off_t sblockloc, int flags, fs->fs_magic == FS_UFS1_MAGIC ? 1 : 2, #lhs1, \ (intmax_t)lhs1, #op1, #rhs1, (intmax_t)rhs1, #lhs2, \ (intmax_t)lhs2, #op2, #rhs2, (intmax_t)rhs2); \ + if (error < 0) \ + return (ENOENT); \ if (error == 0) \ error = ENOENT; \ } @@ -385,12 +389,16 @@ validate_sblock(struct fs *fs, int flags) */ if ((flags & UFS_FSRONLY) == UFS_FSRONLY && (fs->fs_magic == FS_UFS1_MAGIC || fs->fs_magic == FS_UFS2_MAGIC)) { + error = -1; /* fail on first error */ if (fs->fs_magic == FS_UFS2_MAGIC) { FCHK(fs->fs_sblockloc, !=, SBLOCK_UFS2, %#jx); } else if (fs->fs_magic == FS_UFS1_MAGIC) { FCHK(fs->fs_sblockloc, <, 0, %jd); FCHK(fs->fs_sblockloc, >, SBLOCK_UFS1, %jd); } + FCHK(fs->fs_sbsize, >, SBLOCKSIZE, %jd); + FCHK(fs->fs_sbsize, <, (signed)sizeof(struct fs), %jd); + FCHK(fs->fs_sbsize % fs->fs_fsize, !=, 0, %jd); FCHK(fs->fs_frag, <, 1, %jd); FCHK(fs->fs_frag, >, MAXFRAG, %jd); FCHK(fs->fs_bsize, <, MINBSIZE, %jd); @@ -438,12 +446,12 @@ validate_sblock(struct fs *fs, int flags) WCHK(fs->fs_old_rotdelay, !=, 0, %jd); WCHK(fs->fs_old_rps, !=, 60, %jd); WCHK(fs->fs_old_nspf, !=, fs->fs_fsize / sectorsize, %jd); - WCHK(fs->fs_old_cpg, !=, 1, %jd); + FCHK(fs->fs_old_cpg, !=, 1, %jd); WCHK(fs->fs_old_interleave, !=, 1, %jd); WCHK(fs->fs_old_trackskew, !=, 0, %jd); WCHK(fs->fs_old_cpc, !=, 0, %jd); WCHK(fs->fs_old_postblformat, !=, 1, %jd); - WCHK(fs->fs_old_nrpos, !=, 1, %jd); + FCHK(fs->fs_old_nrpos, !=, 1, %jd); WCHK(fs->fs_old_spc, !=, fs->fs_fpg * fs->fs_old_nspf, %jd); WCHK(fs->fs_old_nsect, !=, fs->fs_old_spc, %jd); WCHK(fs->fs_old_npsect, !=, fs->fs_old_spc, %jd); @@ -464,10 +472,18 @@ validate_sblock(struct fs *fs, int flags) FCHK(powerof2(fs->fs_fsize), ==, 0, %jd); FCHK(fs->fs_fpg, <, 3 * fs->fs_frag, %jd); FCHK(fs->fs_ncg, <, 1, %jd); - FCHK(fs->fs_ipg, <, 1, %jd); + FCHK(fs->fs_ipg, <, fs->fs_inopb, %jd); + FCHK(fs->fs_ipg % fs->fs_inopb, !=, 0, %jd); FCHK(fs->fs_ipg * fs->fs_ncg, >, (((int64_t)(1)) << 32) - INOPB(fs), %jd); + FCHK(fs->fs_cstotal.cs_nifree, <, 0, %jd); + FCHK(fs->fs_cstotal.cs_nifree, >, fs->fs_ipg * fs->fs_ncg, %jd); + FCHK(fs->fs_cstotal.cs_ndir, <, 0, %jd); + FCHK(fs->fs_cstotal.cs_ndir, >, + (fs->fs_ipg * fs->fs_ncg) - fs->fs_cstotal.cs_nifree, %jd); FCHK(fs->fs_sbsize, >, SBLOCKSIZE, %jd); + FCHK(fs->fs_sbsize, <, (signed)sizeof(struct fs), %jd); + FCHK(fs->fs_sbsize % fs->fs_fsize, !=, 0, %jd); FCHK(fs->fs_maxbsize, <, fs->fs_bsize, %jd); FCHK(powerof2(fs->fs_maxbsize), ==, 0, %jd); FCHK(fs->fs_maxbsize, >, FS_MAXCONTIG * fs->fs_bsize, %jd); @@ -482,6 +498,13 @@ validate_sblock(struct fs *fs, int flags) FCHK(fs->fs_old_cgoffset, <, 0, %jd); FCHK2(fs->fs_old_cgoffset, >, 0, ~fs->fs_old_cgmask, <, 0, %jd); FCHK(fs->fs_old_cgoffset * (~fs->fs_old_cgmask), >, fs->fs_fpg, %jd); + /* + * If anything has failed up to this point, it is usafe to proceed + * as checks below may divide by zero or make other fatal calculations. + * So if we have any errors at this point, give up. + */ + if (error) + return (error); FCHK(fs->fs_sblkno, !=, roundup( howmany(fs->fs_sblockloc + SBLOCKSIZE, fs->fs_fsize), fs->fs_frag), %jd); @@ -490,6 +513,8 @@ validate_sblock(struct fs *fs, int flags) FCHK(fs->fs_iblkno, !=, fs->fs_cblkno + fs->fs_frag, %jd); FCHK(fs->fs_dblkno, !=, fs->fs_iblkno + fs->fs_ipg / INOPF(fs), %jd); FCHK(fs->fs_cgsize, >, fs->fs_bsize, %jd); + FCHK(fs->fs_cgsize, <, fs->fs_fsize, %jd); + FCHK(fs->fs_cgsize % fs->fs_fsize, !=, 0, %jd); /* * This test is valid, however older versions of growfs failed * to correctly update fs_dsize so will fail this test. Thus we @@ -521,8 +546,8 @@ validate_sblock(struct fs *fs, int flags) * and ends in the data area of the same cylinder group. */ FCHK(fs->fs_size, <, 8 * fs->fs_frag, %jd); - WCHK(fs->fs_size, <=, (fs->fs_ncg - 1) * fs->fs_fpg, %jd); - WCHK(fs->fs_size, >, fs->fs_ncg * fs->fs_fpg, %jd); + FCHK(fs->fs_size, <=, (fs->fs_ncg - 1) * fs->fs_fpg, %jd); + FCHK(fs->fs_size, >, fs->fs_ncg * fs->fs_fpg, %jd); /* * If we are not requested to read in the csum data stop here * as the correctness of the remaining values is only important @@ -558,8 +583,8 @@ validate_sblock(struct fs *fs, int flags) */ WCHK(fs->fs_maxcontig, <, 0, %jd); WCHK(fs->fs_maxcontig, >, MAX(256, maxphys / fs->fs_bsize), %jd); - WCHK2(fs->fs_maxcontig, ==, 0, fs->fs_contigsumsize, !=, 0, %jd); - WCHK2(fs->fs_maxcontig, >, 1, fs->fs_contigsumsize, !=, + FCHK2(fs->fs_maxcontig, ==, 0, fs->fs_contigsumsize, !=, 0, %jd); + FCHK2(fs->fs_maxcontig, >, 1, fs->fs_contigsumsize, !=, MIN(fs->fs_maxcontig, FS_MAXCONTIG), %jd); return (error); } @@ -620,8 +645,8 @@ ffs_sbsearch(void *devfd, struct fs **fsp, int reqflags, if (ffs_sbget(devfd, &protofs, UFS_STDSB, flags, filltype, readfunc) == 0) { if (msg) - printf("Attempted extraction of recovery data from " - "standard superblock: "); + printf("Attempt extraction of recovery data from " + "standard superblock.\n"); } else { /* * Final desperation is to see if alternate superblock @@ -630,7 +655,7 @@ ffs_sbsearch(void *devfd, struct fs **fsp, int reqflags, if (msg) printf("Attempted extraction of recovery data from " "standard superblock: failed\nAttempt to find " - "boot zone recovery data: "); + "boot zone recovery data.\n"); /* * Look to see if recovery information has been saved. * If so we can generate a prototype superblock based @@ -675,13 +700,19 @@ ffs_sbsearch(void *devfd, struct fs **fsp, int reqflags, /* * Scan looking for alternative superblocks. */ + flags = nocsum; + if (!msg) + flags |= UFS_NOMSG; for (cg = 0; cg < protofs->fs_ncg; cg++) { - sblk = dbtob(fsbtodb(protofs, cgsblock(protofs, cg))); - if (ffs_sbget(devfd, fsp, sblk, UFS_NOMSG | nocsum, filltype, + sblk = fsbtodb(protofs, cgsblock(protofs, cg)); + if (msg) + printf("Try cg %ld at sblock loc %jd\n", cg, + (intmax_t)sblk); + if (ffs_sbget(devfd, fsp, dbtob(sblk), flags, filltype, readfunc) == 0) { if (msg) - printf("succeeded with alternate superblock " - "at %jd\n", (intmax_t)btodb(sblk)); + printf("Succeeded with alternate superblock " + "at %jd\n", (intmax_t)sblk); UFS_FREE(protofs, filltype); return (0); } @@ -694,13 +725,18 @@ ffs_sbsearch(void *devfd, struct fs **fsp, int reqflags, trynowarn: flags = UFS_NOWARNFAIL | UFS_NOMSG | nocsum; if (msg) { - printf("failed\n"); + printf("Finding an alternate superblock failed.\nCheck for " + "only non-critical errors in standard superblock\n"); flags &= ~UFS_NOMSG; } - if (ffs_sbget(devfd, fsp, UFS_STDSB, flags, filltype, readfunc) != 0) + if (ffs_sbget(devfd, fsp, UFS_STDSB, flags, filltype, readfunc) != 0) { + if (msg) + printf("Failed, superblock has critical errors\n"); return (ENOENT); + } if (msg) - printf("Using standard superblock with non-critical errors.\n"); + printf("Success, using standard superblock with " + "non-critical errors.\n"); return (0); }
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