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authorDenton Liu <liu.denton@gmail.com>2020-05-19 10:54:00 (GMT)
committerJunio C Hamano <gitster@pobox.com>2020-05-24 23:26:00 (GMT)
commitb0df0c16ead4c5512d506dcbbdf31194d992803c (patch)
treec2a5f0b8bfb8fd410c5b3b1217202d8f91e3df39 /builtin/fetch-pack.c
parent0181b600a6deb66a346dbcbe8300cf9e2467ebbb (diff)
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stateless-connect: send response end packet
Currently, remote-curl acts as a proxy and blindly forwards packets between an HTTP server and fetch-pack. In the case of a stateless RPC connection where the connection is terminated before the transaction is complete, remote-curl will blindly forward the packets before waiting on more input from fetch-pack. Meanwhile, fetch-pack will read the transaction and continue reading, expecting more input to continue the transaction. This results in a deadlock between the two processes. This can be seen in the following command which does not terminate: $ git -c protocol.version=2 clone https://github.com/git/git.git --shallow-since=20151012 Cloning into 'git'... whereas the v1 version does terminate as expected: $ git -c protocol.version=1 clone https://github.com/git/git.git --shallow-since=20151012 Cloning into 'git'... fatal: the remote end hung up unexpectedly Instead of blindly forwarding packets, make remote-curl insert a response end packet after proxying the responses from the remote server when using stateless_connect(). On the RPC client side, ensure that each response ends as described. A separate control packet is chosen because we need to be able to differentiate between what the remote server sends and remote-curl's control packets. By ensuring in the remote-curl code that a server cannot send response end packets, we prevent a malicious server from being able to perform a denial of service attack in which they spoof a response end packet and cause the described deadlock to happen. Reported-by: Force Charlie <charlieio@outlook.com> Helped-by: Jeff King <peff@peff.net> Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/fetch-pack.c')
-rw-r--r--builtin/fetch-pack.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 4771100..94b0c89 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -224,7 +224,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
version = discover_version(&reader);
switch (version) {
case protocol_v2:
- get_remote_refs(fd[1], &reader, &ref, 0, NULL, NULL);
+ get_remote_refs(fd[1], &reader, &ref, 0, NULL, NULL, args.stateless_rpc);
break;
case protocol_v1:
case protocol_v0: