Hi,
Static analysis with Coverity on Linux-next has found an issue with the
following commit:
commit 6b4b87f2c31ac1af4f244990a7cbfb50d3f3e33f
Author: Dave Jiang <[email protected]>
Date: Wed Jul 14 11:50:06 2021 -0700
dmaengine: idxd: fix submission race window
The analysis is as follows:
180static int irq_process_pending_llist(struct idxd_irq_entry *irq_entry,
181 int *processed, u64 data)
182{
183 struct idxd_desc *desc, *t;
184 struct llist_node *head;
185 int queued = 0;
186 unsigned long flags;
187
188 *processed = 0;
189 head = llist_del_all(&irq_entry->pending_llist);
190 if (!head)
191 goto out;
192
193 llist_for_each_entry_safe(desc, t, head, llnode) {
assignment: Assigning: status = (*desc).completion->status & 0x7f.
194 u8 status = desc->completion->status &
DSA_COMP_STATUS_MASK;
195
cond_between: Condition status, taking true branch. Now the value of
status is between 1 and 127.
cond_cannot_single: Condition status, taking true branch. Now the
value of status cannot be equal to 0.
196 if (status) {
between: At condition status == IDXD_COMP_DESC_ABORT, the value of
status must be between 1 and 127.
cond_cannot_set: Condition status == IDXD_COMP_DESC_ABORT, taking
false branch. Now the value of status cannot be equal to any of {0, 255}.
cannot_single: At condition status == IDXD_COMP_DESC_ABORT, the value
of status cannot be equal to 0.
dead_error_condition: The condition !!(status ==
IDXD_COMP_DESC_ABORT) cannot be true.
197 if (unlikely(status == IDXD_COMP_DESC_ABORT)) {
Logically dead code (DEADCODE)
dead_error_begin: Execution cannot reach this statement:
complete_desc(desc, IDXD_CO....
198 complete_desc(desc, IDXD_COMPLETE_ABORT);
199 (*processed)++;
200 continue;
201 }
202
203 complete_desc(desc, IDXD_COMPLETE_NORMAL);
204 (*processed)++;
The check (status == IDXD_COMP_DESC_ABORT) is always false since status
was previously masked with 0x7f and IDXD_COMP_DESC_ABORT is 0xff
Colin.