From e91df8449abbbb2087c64428c8e4af25c445ca0e Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 26 Feb 2018 22:43:18 -0600 Subject: [PATCH] xfs: check sb_agblocks and sb_agblklog when validating superblock Source kernel commit: 4bb73d014785cc55225686f9f46e7192fb59d26b Currently, we don't check sb_agblocks or sb_agblklog when we validate the superblock, which means that we can fuzz garbage values into those values and the mount succeeds. This leads to all sorts of UBSAN warnings in xfs/350 since we can then coerce other parts of xfs into shifting by ridiculously large values. Once we've validated agblocks, make sure the agcount makes sense. Signed-off-by: Darrick J. Wong Reviewed-by: Brian Foster [sandeen: fix up u32 usage now so we keep building] Signed-off-by: Eric Sandeen --- libxfs/libxfs_priv.h | 18 ++++++++++++++++++ libxfs/xfs_fs.h | 7 +++++++ libxfs/xfs_sb.c | 14 ++++++++++++++ 3 files changed, 39 insertions(+) diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h index 637493d73..bc1ce226a 100644 --- a/libxfs/libxfs_priv.h +++ b/libxfs/libxfs_priv.h @@ -231,6 +231,24 @@ static inline int __do_div(unsigned long long *n, unsigned base) #define do_mod(a, b) ((a) % (b)) #define rol32(x,y) (((x) << (y)) | ((x) >> (32 - (y)))) +/** + * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder + * @dividend: unsigned 64bit dividend + * @divisor: unsigned 32bit divisor + * @remainder: pointer to unsigned 32bit remainder + * + * Return: sets ``*remainder``, then returns dividend / divisor + * + * This is commonly provided by 32bit archs to provide an optimized 64bit + * divide. + */ +static inline uint64_t +div_u64_rem(uint64_t dividend, uint32_t divisor, uint32_t *remainder) +{ + *remainder = dividend % divisor; + return dividend / divisor; +} + #define min_t(type,x,y) \ ({ type __x = (x); type __y = (y); __x < __y ? __x: __y; }) #define max_t(type,x,y) \ diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h index 489f0f572..86a379f6c 100644 --- a/libxfs/xfs_fs.h +++ b/libxfs/xfs_fs.h @@ -254,6 +254,13 @@ typedef struct xfs_fsop_resblks { #define XFS_MAX_LOG_BLOCKS (1024 * 1024ULL) #define XFS_MIN_LOG_BYTES (10 * 1024 * 1024ULL) +/* + * Limits on sb_agblocks/sb_agblklog -- mkfs won't format AGs smaller than + * 16MB or larger than 1TB. + */ +#define XFS_MIN_AG_BYTES (1ULL << 24) /* 16 MB */ +#define XFS_MAX_AG_BYTES (1ULL << 40) /* 1 TB */ + /* keep the maximum size under 2^31 by a small amount */ #define XFS_MAX_LOG_BYTES \ ((2 * 1024 * 1024 * 1024ULL) - XFS_MIN_LOG_BYTES) diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c index 57c88d220..bca65eeb6 100644 --- a/libxfs/xfs_sb.c +++ b/libxfs/xfs_sb.c @@ -115,6 +115,9 @@ xfs_mount_validate_sb( bool check_inprogress, bool check_version) { + uint32_t agcount = 0; + uint32_t rem; + if (sbp->sb_magicnum != XFS_SB_MAGIC) { xfs_warn(mp, "bad magic number"); return -EWRONGFS; @@ -225,6 +228,13 @@ xfs_mount_validate_sb( return -EINVAL; } + /* Compute agcount for this number of dblocks and agblocks */ + if (sbp->sb_agblocks) { + agcount = div_u64_rem(sbp->sb_dblocks, sbp->sb_agblocks, &rem); + if (rem) + agcount++; + } + /* * More sanity checking. Most of these were stolen directly from * xfs_repair. @@ -249,6 +259,10 @@ xfs_mount_validate_sb( sbp->sb_inodesize != (1 << sbp->sb_inodelog) || sbp->sb_logsunit > XLOG_MAX_RECORD_BSIZE || sbp->sb_inopblock != howmany(sbp->sb_blocksize,sbp->sb_inodesize) || + XFS_FSB_TO_B(mp, sbp->sb_agblocks) < XFS_MIN_AG_BYTES || + XFS_FSB_TO_B(mp, sbp->sb_agblocks) > XFS_MAX_AG_BYTES || + sbp->sb_agblklog != xfs_highbit32(sbp->sb_agblocks - 1) + 1 || + agcount == 0 || agcount != sbp->sb_agcount || (sbp->sb_blocklog - sbp->sb_inodelog != sbp->sb_inopblog) || (sbp->sb_rextsize * sbp->sb_blocksize > XFS_MAX_RTEXTSIZE) || (sbp->sb_rextsize * sbp->sb_blocksize < XFS_MIN_RTEXTSIZE) || -- 2.47.2