In commit:
8eb9ea1b354b SCardTransmit() may return SCARD_E_INSUFFICIENT_BUFFER
the recv buffer size, passed to the SCardTransmit() function, is set
unconditionally to "sizeof pbRecvBuffer", which is 64k + 12. This leads to
problems when the CT API is used in the lower layers, as the CT API implements
a maximum recv buffer size of 64k.
This leads to the truncation of the recv buffer size to 12. If the client has
supplied a buffer of >12 bytes, resulting in truncated reads. This patch tries
to work around the problem, by not unconditionally passing the recv buffer size
of "sizeof pbRecvBuffer" (64k + 12), but increasing the client supplied buffer
by one, keeping the "sizeof pbRecvBuffer" as an upper bound. This way a too
small recv buffer passed by the client can still be detected, but the CT API
limit of 64k is not exceeded if the buffer is below 64k.
Cc: Marcin Cieslak <[email protected]>
---
src/winscard_svc.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/src/winscard_svc.c b/src/winscard_svc.c
index 75e4c8e4e8e1..a623fd60f631 100644
--- a/src/winscard_svc.c
+++ b/src/winscard_svc.c
@@ -636,7 +636,20 @@ static void ContextThread(LPVOID newContext)
ioSendPci.cbPciLength = trStr.ioSendPciLength;
ioRecvPci.dwProtocol = trStr.ioRecvPciProtocol;
ioRecvPci.cbPciLength = trStr.ioRecvPciLength;
+ /* The CT API implements a max recv buffer size
of 64k,
+ * while "sizeof pbRecvBuffer" is "64k + 12".
This leads
+ * to trunkation of max recv buffer size to
"12" when
+ * using "sizeof pbRecvBuffer", even if the
client
+ * specifies a much smaller recv buffer.
+ *
+ * Here we increase the client buffer by one
+ * (but keeping "sizeof pbRecvBuffer" as
maximum),
+ * so that we can detect a too small client
buffer
+ * later.
+ */
cbRecvLength = sizeof pbRecvBuffer;
+ if (cbRecvLength > trStr.pcbRecvLength + 1)
+ cbRecvLength = trStr.pcbRecvLength + 1;
trStr.rv = SCardTransmit(trStr.hCard,
&ioSendPci,
pbSendBuffer, trStr.cbSendLength,
&ioRecvPci,
--
2.6.2
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