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authorFilipe Manana <fdmanana@suse.com>2024-11-04 12:11:15 +0000
committerDavid Sterba <dsterba@suse.com>2024-11-07 02:07:53 +0100
commitc9a75ec45f1111ef530ab186c2a7684d0a0c9245 (patch)
treeb93f61c7060a42cccc51fa057c460ce6f00eec75 /fs
parentcda7163d4e3d99db93aa38f0e825b8433c7a8452 (diff)
btrfs: reinitialize delayed ref list after deleting it from the list
At insert_delayed_ref() if we need to update the action of an existing ref to BTRFS_DROP_DELAYED_REF, we delete the ref from its ref head's ref_add_list using list_del(), which leaves the ref's add_list member not reinitialized, as list_del() sets the next and prev members of the list to LIST_POISON1 and LIST_POISON2, respectively. If later we end up calling drop_delayed_ref() against the ref, which can happen during merging or when destroying delayed refs due to a transaction abort, we can trigger a crash since at drop_delayed_ref() we call list_empty() against the ref's add_list, which returns false since the list was not reinitialized after the list_del() and as a consequence we call list_del() again at drop_delayed_ref(). This results in an invalid list access since the next and prev members are set to poison pointers, resulting in a splat if CONFIG_LIST_HARDENED and CONFIG_DEBUG_LIST are set or invalid poison pointer dereferences otherwise. So fix this by deleting from the list with list_del_init() instead. Fixes: 1d57ee941692 ("btrfs: improve delayed refs iterations") CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/delayed-ref.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 115b90d29b1d..65d841d7142c 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -649,7 +649,7 @@ static bool insert_delayed_ref(struct btrfs_trans_handle *trans,
&href->ref_add_list);
else if (ref->action == BTRFS_DROP_DELAYED_REF) {
ASSERT(!list_empty(&exist->add_list));
- list_del(&exist->add_list);
+ list_del_init(&exist->add_list);
} else {
ASSERT(0);
}