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xfs: More robust inode extent count validation 

When the inode is in extent format, it can't have more extents that
fit in the inode fork. We don't currenty check this, and so this
corruption goes unnoticed by the inode verifiers. This can lead to
crashes operating on invalid in-memory structures.

Attempts to access such a inode will now error out in the verifier
rather than allowing modification operations to proceed.

Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: fix a typedef, add some braces and breaks to shut up compiler warnings]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner 2018-06-21 23:25:57 -07:00 committed by Darrick J. Wong
parent e2ac836307
commit 23fcb3340d
2 changed files with 50 additions and 29 deletions
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3
fs/xfs/libxfs/xfs_format.h
View File

@ -962,6 +962,9 @@ typedef enum xfs_dinode_fmt {
XFS_DFORK_DSIZE(dip, mp) : \
XFS_DFORK_ASIZE(dip, mp))
#define XFS_DFORK_MAXEXT(dip, mp, w) \
(XFS_DFORK_SIZE(dip, mp, w) / sizeof(struct xfs_bmbt_rec))
/*
* Return pointers to the data or attribute forks.
*/

76
fs/xfs/libxfs/xfs_inode_buf.c
View File

@ -374,6 +374,47 @@ xfs_log_dinode_to_disk(
}
}
static xfs_failaddr_t
xfs_dinode_verify_fork(
struct xfs_dinode *dip,
struct xfs_mount *mp,
int whichfork)
{
uint32_t di_nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
switch (XFS_DFORK_FORMAT(dip, whichfork)) {
case XFS_DINODE_FMT_LOCAL:
/*
* no local regular files yet
*/
if (whichfork == XFS_DATA_FORK) {
if (S_ISREG(be16_to_cpu(dip->di_mode)))
return __this_address;
if (be64_to_cpu(dip->di_size) >
XFS_DFORK_SIZE(dip, mp, whichfork))
return __this_address;
}
if (di_nextents)
return __this_address;
break;
case XFS_DINODE_FMT_EXTENTS:
if (di_nextents > XFS_DFORK_MAXEXT(dip, mp, whichfork))
return __this_address;
break;
case XFS_DINODE_FMT_BTREE:
if (whichfork == XFS_ATTR_FORK) {
if (di_nextents > MAXAEXTNUM)
return __this_address;
} else if (di_nextents > MAXEXTNUM) {
return __this_address;
}
break;
default:
return __this_address;
}
return NULL;
}
xfs_failaddr_t
xfs_dinode_verify(
struct xfs_mount *mp,
@ -441,24 +482,9 @@ xfs_dinode_verify(
case S_IFREG:
case S_IFLNK:
case S_IFDIR:
switch (dip->di_format) {
case XFS_DINODE_FMT_LOCAL:
/*
* no local regular files yet
*/
if (S_ISREG(mode))
return __this_address;
if (di_size > XFS_DFORK_DSIZE(dip, mp))
return __this_address;
if (dip->di_nextents)
return __this_address;
/* fall through */
case XFS_DINODE_FMT_EXTENTS:
case XFS_DINODE_FMT_BTREE:
break;
default:
return __this_address;
}
fa = xfs_dinode_verify_fork(dip, mp, XFS_DATA_FORK);
if (fa)
return fa;
break;
case 0:
/* Uninitialized inode ok. */
@ -468,17 +494,9 @@ xfs_dinode_verify(
}
if (XFS_DFORK_Q(dip)) {
switch (dip->di_aformat) {
case XFS_DINODE_FMT_LOCAL:
if (dip->di_anextents)
return __this_address;
/* fall through */
case XFS_DINODE_FMT_EXTENTS:
case XFS_DINODE_FMT_BTREE:
break;
default:
return __this_address;
}
fa = xfs_dinode_verify_fork(dip, mp, XFS_ATTR_FORK);
if (fa)
return fa;
} else {
/*
* If there is no fork offset, this may be a freshly-made inode