On Fri, Nov 02, 2018 at 03:31:16PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> generic/070 on 64k block size filesystems is failing with a verifier
> corruption on writeback or an attribute leaf block:
>
> [ 94.973083] XFS (pmem0): Metadata corruption detected at xfs_attr3_leaf_verify+0x246/0x260, xfs_attr3_leaf block 0x811480
> [ 94.975623] XFS (pmem0): Unmount and run xfs_repair
> [ 94.976720] XFS (pmem0): First 128 bytes of corrupted metadata buffer:
> [ 94.978270] 000000004b2e7b45: 00 00 00 00 00 00 00 00 3b ee 00 00 00 00 00 00 ........;.......
> [ 94.980268] 000000006b1db90b: 00 00 00 00 00 81 14 80 00 00 00 00 00 00 00 00 ................
> [ 94.982251] 00000000433f2407: 22 7b 5c 82 2d 5c 47 4c bb 31 1c 37 fa a9 ce d6 "{\.-\GL.1.7....
> [ 94.984157] 0000000010dc7dfb: 00 00 00 00 00 81 04 8a 00 0a 18 e8 dd 94 01 00 ................
> [ 94.986215] 00000000d5a19229: 00 a0 dc f4 fe 98 01 68 f0 d8 07 e0 00 00 00 00 .......h........
> [ 94.988171] 00000000521df36c: 0c 2d 32 e2 fe 20 01 00 0c 2d 58 65 fe 0c 01 00 .-2.. ...-Xe....
> [ 94.990162] 000000008477ae06: 0c 2d 5b 66 fe 8c 01 00 0c 2d 71 35 fe 7c 01 00 .-[f.....-q5.|..
> [ 94.992139] 00000000a4a6bca6: 0c 2d 72 37 fc d4 01 00 0c 2d d8 b8 f0 90 01 00 .-r7.....-......
> [ 94.994789] XFS (pmem0): xfs_do_force_shutdown(0x8) called from line 1453 of file fs/xfs/xfs_buf.c. Return address = ffffffff815365f3
>
> This is failing this check:
>
> end = ichdr.freemap[i].base + ichdr.freemap[i].size;
> if (end < ichdr.freemap[i].base)
> >>>>> return __this_address;
> if (end > mp->m_attr_geo->blksize)
> return __this_address;
>
> And from the buffer output above, the freemap array is:
>
> freemap[0].base = 0x00a0
> freemap[0].size = 0xdcf4 end = 0xdd94
> freemap[1].base = 0xfe98
> freemap[1].size = 0x0168 end = 0x10000
> freemap[2].base = 0xf0d8
> freemap[2].size = 0x07e0 end = 0xf8b8
>
> These all look valid - the block size is 0x10000 and so from the
> last check in the above verifier fragment we know that the end
> of freemap[1] is valid. The problem is that end is declared as:
>
> uint16_t end;
>
> And (uint16_t)0x10000 = 0. So we have a verifier bug here, not a
> corruption. Fix the verifier to use uint32_t types for the check and
> hence avoid the overflow.
>
> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=201577
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
DOH. :(
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/xfs/libxfs/xfs_attr_leaf.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 6fc5425b1474..2652d00842d6 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -243,7 +243,7 @@ xfs_attr3_leaf_verify(
> struct xfs_mount *mp = bp->b_target->bt_mount;
> struct xfs_attr_leafblock *leaf = bp->b_addr;
> struct xfs_attr_leaf_entry *entries;
> - uint16_t end;
> + uint32_t end; /* must be 32bit - see below */
> int i;
>
> xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
> @@ -293,6 +293,11 @@ xfs_attr3_leaf_verify(
> /*
> * Quickly check the freemap information. Attribute data has to be
> * aligned to 4-byte boundaries, and likewise for the free space.
> + *
> + * Note that for 64k block size filesystems, the freemap entries cannot
> + * overflow as they are only be16 fields. However, when checking end
> + * pointer of the freemap, we have to be careful to detect overflows and
> + * so use uint32_t for those checks.
> */
> for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
> if (ichdr.freemap[i].base > mp->m_attr_geo->blksize)
> @@ -303,7 +308,9 @@ xfs_attr3_leaf_verify(
> return __this_address;
> if (ichdr.freemap[i].size & 0x3)
> return __this_address;
> - end = ichdr.freemap[i].base + ichdr.freemap[i].size;
> +
> + /* be care of 16 bit overflows here */
> + end = (uint32_t)ichdr.freemap[i].base + ichdr.freemap[i].size;
> if (end < ichdr.freemap[i].base)
> return __this_address;
> if (end > mp->m_attr_geo->blksize)
> --
> 2.19.1
>
