git: bc218d89200f - main - Two bug fixes to UFS/FFS superblock integrity checks when reading a superblock.
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Date: Wed, 01 Jun 2022 02:58:40 UTC
The branch main has been updated by mckusick: URL: https://cgit.FreeBSD.org/src/commit/?id=bc218d89200faa021def77732f3d9fde4f4dee13 commit bc218d89200faa021def77732f3d9fde4f4dee13 Author: Kirk McKusick <mckusick@FreeBSD.org> AuthorDate: 2022-06-01 02:55:54 +0000 Commit: Kirk McKusick <mckusick@FreeBSD.org> CommitDate: 2022-06-01 02:58:37 +0000 Two bug fixes to UFS/FFS superblock integrity checks when reading a superblock. Two bugs have been reported with the UFS/FFS superblock integrity checks that were added in commit 076002f24d35. The code checked that fs_sblockactualloc was properly set to the location of the superblock. The fs_sblockactualloc field was an addition to the superblock in commit dffce2150eea on Jan 26 2018 and used a field that was zero in filesystems created before it was added. The integrity check had to be expanded to accept the fs_sblockactualloc field being zero so as not to reject filesystems created before Jan 26 2018. The integrity check set an upper bound on the value of fs_maxcontig based on the maximum transfer size supported by the kernel. It required that fs->fs_maxcontig <= maxphys / fs->fs_bsize. The kernel variable maxphys defines the maximum transfer size permitted by the controllers and/or buffering. The fs_maxcontig parameter controls the maximum number of blocks that the filesystem will read or write in a single transfer. It is calculated when the filesystem is created as maxphys / fs_bsize. The bug appeared in the loader because it uses a maxphys of 128K even when running on a system that supports larger values. If the filesystem was built on a system that supports a larger maxphys (1M is typical) it will have configured fs_maxcontig for that larger system so would fail the test when run with the smaller maxphys used by the loader. So we bound the upper allowable limit for fs_maxconfig to be able to at least work with a 1M maxphys on the smallest block size filesystem: 1M / 4096 == 256. We then use the limit for fs_maxcontig as fs_maxcontig <= MAX(256, maxphys / fs_bsize). There is no harm in allowing the mounting of filesystems that make larger than maxphys I/O requests because those (mostly 32-bit machines) can (very slowly) handle I/O requests that exceed maxphys. Thanks to everyone who helped sort out the problems and the fixes. Reported by: Cy Schubert, David Wolfskill Diagnosis by: Mark Johnston, John Baldwin Reviewed by: Warner Losh Tested by: Cy Schubert, David Wolfskill MFC after: 1 month (with 076002f24d35) Differential Revision: https://reviews.freebsd.org/D35219 --- sys/ufs/ffs/ffs_subr.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/sys/ufs/ffs/ffs_subr.c b/sys/ufs/ffs/ffs_subr.c index 28c2fee1cb37..f25a6cba12f4 100644 --- a/sys/ufs/ffs/ffs_subr.c +++ b/sys/ufs/ffs/ffs_subr.c @@ -319,7 +319,8 @@ validate_sblock(struct fs *fs, int isaltsblk) sectorsize = dbtob(1); if (fs->fs_magic == FS_UFS2_MAGIC) { if ((!isaltsblk && (fs->fs_sblockloc != SBLOCK_UFS2 || - fs->fs_sblockactualloc != SBLOCK_UFS2)) || + !(fs->fs_sblockactualloc == 0 || + 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) || @@ -327,7 +328,8 @@ validate_sblock(struct fs *fs, int isaltsblk) return (ENOENT); } else if (fs->fs_magic == FS_UFS1_MAGIC) { if ((!isaltsblk && (fs->fs_sblockloc > SBLOCK_UFS1 || - fs->fs_sblockactualloc != SBLOCK_UFS1)) || + !(fs->fs_sblockactualloc == SBLOCK_UFS1 || + fs->fs_sblockactualloc == 0))) || fs->fs_nindir != fs->fs_bsize / sizeof(ufs1_daddr_t) || fs->fs_inopb != fs->fs_bsize / sizeof(struct ufs1_dinode) || fs->fs_maxsymlinklen != ((UFS_NDADDR + UFS_NIADDR) * @@ -423,13 +425,26 @@ validate_sblock(struct fs *fs, int isaltsblk) fs->fs_size > fs->fs_ncg * fs->fs_fpg) return (ENOENT); /* - * Maxcontig sets the default for the maximum number of blocks - * that may be allocated sequentially. With file system clustering - * it is possible to allocate contiguous blocks up to the maximum - * transfer size permitted by the controller or buffering. + * With file system clustering it is possible to allocate + * many contiguous blocks. The kernel variable maxphys defines + * the maximum transfer size permitted by the controller and/or + * buffering. The fs_maxcontig parameter controls the maximum + * number of blocks that the filesystem will read or write + * in a single transfer. It is calculated when the filesystem + * is created as maxphys / fs_bsize. The loader uses a maxphys + * of 128K even when running on a system that supports larger + * values. If the filesystem was built on a system that supports + * a larger maxphys (1M is typical) it will have configured + * fs_maxcontig for that larger system. So we bound the upper + * allowable limit for fs_maxconfig to be able to at least + * work with a 1M maxphys on the smallest block size filesystem: + * 1M / 4096 == 256. There is no harm in allowing the mounting of + * filesystems that make larger than maxphys I/O requests because + * those (mostly 32-bit machines) can (very slowly) handle I/O + * requests that exceed maxphys. */ if (fs->fs_maxcontig < 1 || - fs->fs_maxcontig > MAX(1, maxphys / fs->fs_bsize)) + fs->fs_maxcontig > MAX(256, maxphys / fs->fs_bsize)) return (ENOENT); if (fs->fs_maxcontig < 0 || (fs->fs_maxcontig == 0 && fs->fs_contigsumsize != 0) ||