On Mon, Jul 29, 2019 at 11:24:01AM +0800, Jia-Ju Bai wrote: > In xchk_da_btree_block_check_sibling(), there is an if statement on > line 274 to check whether ds->state->altpath.blk[level].bp is NULL: > if (ds->state->altpath.blk[level].bp) > > When ds->state->altpath.blk[level].bp is NULL, it is used on line 281: > xfs_trans_brelse(..., ds->state->altpath.blk[level].bp); > struct xfs_buf_log_item *bip = bp->b_log_item; > ASSERT(bp->b_transp == tp); > > Thus, possible null-pointer dereferences may occur. > > To fix these bugs, ds->state->altpath.blk[level].bp is checked before > being used. > > These bugs are found by a static analysis tool STCheck written by us. > > Signed-off-by: Jia-Ju Bai <[email protected]> > --- > fs/xfs/scrub/dabtree.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/scrub/dabtree.c b/fs/xfs/scrub/dabtree.c > index 94c4f1de1922..33ff90c0dd70 100644 > --- a/fs/xfs/scrub/dabtree.c > +++ b/fs/xfs/scrub/dabtree.c > @@ -278,7 +278,9 @@ xchk_da_btree_block_check_sibling( > /* Compare upper level pointer to sibling pointer. */ > if (ds->state->altpath.blk[level].blkno != sibling) > xchk_da_set_corrupt(ds, level); > - xfs_trans_brelse(ds->dargs.trans, ds->state->altpath.blk[level].bp); > + if (ds->state->altpath.blk[level].bp) > + xfs_trans_brelse(ds->dargs.trans, > + > ds->state->altpath.blk[level].bp);
Indentation here (in xfs we use two spaces) Also, uh, shouldn't we set ds->state->altpath.blk[level].bp to NULL since we've released the buffer? --D > out: > return error; > } > -- > 2.17.0 >
