From f2d5772522b65e7475fe4f2c880cf02780df0d47 Mon Sep 17 00:00:00 2001 From: Mingzhe Zou Date: Fri, 11 Feb 2022 14:39:15 +0800 Subject: [PATCH] bcache: fixup multiple threads crash commit 887554ab96588de2917b6c8c73e552da082e5368 upstream. When multiple threads to check btree nodes in parallel, the main thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag: wait_event_interruptible(check_state->wait, atomic_read(&check_state->started) == 0 || test_bit(CACHE_SET_IO_DISABLE, &c->flags)); However, the bch_btree_node_read and bch_btree_node_read_done maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE will be set. If the flag already set, the main thread return error. At the same time, maybe some threads still running and read NULL pointer, the kernel will crash. This patch change the event wait condition, the main thread must wait for all threads to stop. Fixes: 8e7102273f597 ("bcache: make bch_btree_check() to be multithreaded") Signed-off-by: Mingzhe Zou Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Coly Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/bcache/btree.c | 6 ++++-- drivers/md/bcache/writeback.c | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 183a58c893774d..8eecc9df319b56 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -2060,9 +2060,11 @@ int bch_btree_check(struct cache_set *c) } } + /* + * Must wait for all threads to stop. + */ wait_event_interruptible(check_state->wait, - atomic_read(&check_state->started) == 0 || - test_bit(CACHE_SET_IO_DISABLE, &c->flags)); + atomic_read(&check_state->started) == 0); for (i = 0; i < check_state->total_threads; i++) { if (check_state->infos[i].result) { diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 8120da278161e9..1c03a3b72f8aaf 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -998,9 +998,11 @@ void bch_sectors_dirty_init(struct bcache_device *d) } } + /* + * Must wait for all threads to stop. + */ wait_event_interruptible(state->wait, - atomic_read(&state->started) == 0 || - test_bit(CACHE_SET_IO_DISABLE, &c->flags)); + atomic_read(&state->started) == 0); out: kfree(state);