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nbd: safeguard against waking up invalid coroutine 

The .reply_possible field of s->requests is never set to false.  This is
not a problem as it is only a safeguard to detect protocol errors,
but it's sloppy.  In fact, the field is actually not necessary at all,
because .coroutine is set to NULL in NBD_FOREACH_REPLY_CHUNK after
receiving the last chunk.  Thus, replace .reply_possible with .coroutine
and move the check before deciding the fate of this request.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220414175756.671165-2-pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Reviewed-by: Lukas Straub <lukasstraub2@web.de>
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Paolo Bonzini 2022-04-14 19:57:48 +02:00 committed by Eric Blake
parent c08c220be7
commit 8846b7d1c1
1 changed files with 5 additions and 7 deletions
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12
block/nbd.c
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@ -58,7 +58,6 @@ typedef struct {
Coroutine *coroutine;
uint64_t offset; /* original offset of the request */
bool receiving; /* sleeping in the yield in nbd_receive_replies */
bool reply_possible; /* reply header not yet received */
} NBDClientRequest;
typedef enum NBDClientState {
@ -454,15 +453,15 @@ static coroutine_fn int nbd_receive_replies(BDRVNBDState *s, uint64_t handle)
nbd_channel_error(s, -EINVAL);
return -EINVAL;
}
ind2 = HANDLE_TO_INDEX(s, s->reply.handle);
if (ind2 >= MAX_NBD_REQUESTS || !s->requests[ind2].coroutine) {
nbd_channel_error(s, -EINVAL);
return -EINVAL;
}
if (s->reply.handle == handle) {
/* We are done */
return 0;
}
ind2 = HANDLE_TO_INDEX(s, s->reply.handle);
if (ind2 >= MAX_NBD_REQUESTS || !s->requests[ind2].reply_possible) {
nbd_channel_error(s, -EINVAL);
return -EINVAL;
}
nbd_recv_coroutine_wake_one(&s->requests[ind2]);
}
}
@ -505,7 +504,6 @@ static int nbd_co_send_request(BlockDriverState *bs,
s->requests[i].coroutine = qemu_coroutine_self();
s->requests[i].offset = request->from;
s->requests[i].receiving = false;
s->requests[i].reply_possible = true;
request->handle = INDEX_TO_HANDLE(s, i);