5.4-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Aring aahringo@redhat.com
[ Upstream commit 57e2c2f2d94cfd551af91cedfa1af6d972487197 ]
When a waiting plock request (F_SETLKW) is sent to userspace for processing (dlm_controld), the result is returned at a later time. That result could be incorrectly matched to a different waiting request in cases where the owner field is the same (e.g. different threads in a process.) This is fixed by comparing all the properties in the request and reply.
The results for non-waiting plock requests are now matched based on list order because the results are returned in the same order they were sent.
Cc: stable@vger.kernel.org Signed-off-by: Alexander Aring aahringo@redhat.com Signed-off-by: David Teigland teigland@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/dlm/plock.c | 58 +++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 45 insertions(+), 13 deletions(-)
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c index fa8969c0a5f55..28735e8c5e206 100644 --- a/fs/dlm/plock.c +++ b/fs/dlm/plock.c @@ -405,7 +405,7 @@ static ssize_t dev_read(struct file *file, char __user *u, size_t count, if (op->info.flags & DLM_PLOCK_FL_CLOSE) list_del(&op->list); else - list_move(&op->list, &recv_list); + list_move_tail(&op->list, &recv_list); memcpy(&info, &op->info, sizeof(info)); } spin_unlock(&ops_lock); @@ -443,20 +443,52 @@ static ssize_t dev_write(struct file *file, const char __user *u, size_t count, if (check_version(&info)) return -EINVAL;
+ /* + * The results for waiting ops (SETLKW) can be returned in any + * order, so match all fields to find the op. The results for + * non-waiting ops are returned in the order that they were sent + * to userspace, so match the result with the first non-waiting op. + */ spin_lock(&ops_lock); - list_for_each_entry(iter, &recv_list, list) { - if (iter->info.fsid == info.fsid && - iter->info.number == info.number && - iter->info.owner == info.owner) { - list_del_init(&iter->list); - memcpy(&iter->info, &info, sizeof(info)); - if (iter->data) - do_callback = 1; - else - iter->done = 1; - op = iter; - break; + if (info.wait) { + list_for_each_entry(iter, &recv_list, list) { + if (iter->info.fsid == info.fsid && + iter->info.number == info.number && + iter->info.owner == info.owner && + iter->info.pid == info.pid && + iter->info.start == info.start && + iter->info.end == info.end && + iter->info.ex == info.ex && + iter->info.wait) { + op = iter; + break; + } } + } else { + list_for_each_entry(iter, &recv_list, list) { + if (!iter->info.wait) { + op = iter; + break; + } + } + } + + if (op) { + /* Sanity check that op and info match. */ + if (info.wait) + WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK); + else + WARN_ON(op->info.fsid != info.fsid || + op->info.number != info.number || + op->info.owner != info.owner || + op->info.optype != info.optype); + + list_del_init(&op->list); + memcpy(&op->info, &info, sizeof(info)); + if (op->data) + do_callback = 1; + else + op->done = 1; } spin_unlock(&ops_lock);