On Wed, Mar 29, 2017 at 09:33:22AM +0800, Qu Wenruo wrote: > scrub_setup_recheck_block() calls btrfs_map_sblock() and then access > bbio without protection of bio_counter. >
s/access/accesses/ > This can leads to use-after-free if racing with dev replace cancel. > s/leads/lead/ > Fix it by increasing bio_counter before calling btrfs_map_sblock() and > decrease the bio_counter when corresponding recover is finished. > *decreasing Reviewed-by: Liu Bo <[email protected]> Thanks, -liubo > Cc: Liu Bo <[email protected]> > Reported-by: Liu Bo <[email protected]> > Signed-off-by: Qu Wenruo <[email protected]> > --- > fs/btrfs/scrub.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c > index b8c49074d1b3..84b077c993c0 100644 > --- a/fs/btrfs/scrub.c > +++ b/fs/btrfs/scrub.c > @@ -1072,9 +1072,11 @@ static inline void scrub_get_recover(struct > scrub_recover *recover) > atomic_inc(&recover->refs); > } > > -static inline void scrub_put_recover(struct scrub_recover *recover) > +static inline void scrub_put_recover(struct btrfs_fs_info *fs_info, > + struct scrub_recover *recover) > { > if (atomic_dec_and_test(&recover->refs)) { > + btrfs_bio_counter_dec(fs_info); > btrfs_put_bbio(recover->bbio); > kfree(recover); > } > @@ -1464,7 +1466,7 @@ static int scrub_handle_errored_block(struct > scrub_block *sblock_to_check) > sblock->pagev[page_index]->sblock = NULL; > recover = sblock->pagev[page_index]->recover; > if (recover) { > - scrub_put_recover(recover); > + scrub_put_recover(fs_info, recover); > sblock->pagev[page_index]->recover = > NULL; > } > @@ -1556,16 +1558,19 @@ static int scrub_setup_recheck_block(struct > scrub_block *original_sblock, > * with a length of PAGE_SIZE, each returned stripe > * represents one mirror > */ > + btrfs_bio_counter_inc_blocked(fs_info); > ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, > logical, &mapped_length, &bbio, 0, 1); > if (ret || !bbio || mapped_length < sublen) { > btrfs_put_bbio(bbio); > + btrfs_bio_counter_dec(fs_info); > return -EIO; > } > > recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS); > if (!recover) { > btrfs_put_bbio(bbio); > + btrfs_bio_counter_dec(fs_info); > return -ENOMEM; > } > > @@ -1591,7 +1596,7 @@ static int scrub_setup_recheck_block(struct scrub_block > *original_sblock, > spin_lock(&sctx->stat_lock); > sctx->stat.malloc_errors++; > spin_unlock(&sctx->stat_lock); > - scrub_put_recover(recover); > + scrub_put_recover(fs_info, recover); > return -ENOMEM; > } > scrub_page_get(page); > @@ -1633,7 +1638,7 @@ static int scrub_setup_recheck_block(struct scrub_block > *original_sblock, > scrub_get_recover(recover); > page->recover = recover; > } > - scrub_put_recover(recover); > + scrub_put_recover(fs_info, recover); > length -= sublen; > logical += sublen; > page_index++; > -- > 2.12.1 > > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
