From afa1d96d1430c2138c545fb76e6dcb21222098d4 Mon Sep 17 00:00:00 2001 From: Jia-Ju Bai Date: Tue, 30 Jul 2019 11:28:20 -0700 Subject: [PATCH] xfs: Fix possible null-pointer dereferences in xchk_da_btree_block_check_sibling() 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 Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/scrub/dabtree.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/xfs/scrub/dabtree.c b/fs/xfs/scrub/dabtree.c index 94c4f1de1922..77ff9f97bcda 100644 --- a/fs/xfs/scrub/dabtree.c +++ b/fs/xfs/scrub/dabtree.c @@ -278,7 +278,11 @@ 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); + ds->state->altpath.blk[level].bp = NULL; + } out: return error; } -- 2.30.2