On Mon, Jun 04, 2018 at 09:08:17PM -0700, Darrick J. Wong wrote:
> On Tue, Jun 05, 2018 at 12:43:12PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@xxxxxxxxxx>
> >
> > There are rules for vald extent size hints. We enforce them when
> > applications set them, but fuzzers violate those rules and that
> > screws us over.
> >
> > This results in alignment assertion failures when setting up
> > allocations such as this in direct IO:
> >
> > XFS: Assertion failed: ap->length, file: fs/xfs/libxfs/xfs_bmap.c, line: 3432
> > ....
> > Call Trace:
> > xfs_bmap_btalloc+0x415/0x910
> > xfs_bmapi_write+0x71c/0x12e0
> > xfs_iomap_write_direct+0x2a9/0x420
> > xfs_file_iomap_begin+0x4dc/0xa70
> > iomap_apply+0x43/0x100
> > iomap_file_buffered_write+0x62/0x90
> > xfs_file_buffered_aio_write+0xba/0x300
> > __vfs_write+0xd5/0x150
> > vfs_write+0xb6/0x180
> > ksys_write+0x45/0xa0
> > do_syscall_64+0x5a/0x180
> > entry_SYSCALL_64_after_hwframe+0x49/0xbe
> >
> > And from xfs_db:
> >
> > core.extsize = 10380288
> >
> > Which is not an integer multiple of the block size, and so violates
> > Rule #7 for setting extent size hints. Validate extent size hint
> > rules in the inode verifier to catch this.
> >
> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> > ---
> > fs/xfs/libxfs/xfs_inode_buf.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
> > index f5fff1ccb61d..be197c91307b 100644
> > --- a/fs/xfs/libxfs/xfs_inode_buf.c
> > +++ b/fs/xfs/libxfs/xfs_inode_buf.c
> > @@ -385,6 +385,7 @@ xfs_dinode_verify(
> > xfs_ino_t ino,
> > struct xfs_dinode *dip)
> > {
> > + xfs_failaddr_t fa;
> > uint16_t mode;
> > uint16_t flags;
> > uint64_t flags2;
> > @@ -501,6 +502,12 @@ xfs_dinode_verify(
> > return __this_address;
> > }
> >
> > + /* extent size hint validation */
> > + fa = xfs_inode_validate_extsize(mp, be32_to_cpu(dip->di_extsize),
> > + mode, be32_to_cpu(dip->di_flags));
>
> What if the cowextsize is garbage? Do we handle that better, or do we
> blow up there too?
I haven't checked (it was a v4 image that I was looking at) - are
the rules the same?
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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