From d55c54cecb5e83eaa2d56bed5cc4461f9ba318c2 Mon Sep 17 00:00:00 2001 From: Olivier Fourdan Date: Mon, 28 Apr 2025 10:46:03 +0200 Subject: [PATCH] os: Account for bytes to ignore when sharing input buffer When reading requests from the clients, the input buffer might be shared and used between different clients. If a given client sends a full request with non-zero bytes to ignore, the bytes to ignore may still be non-zero even though the request is full, in which case the buffer could be shared with another client who's request will not be processed because of those bytes to ignore, leading to a possible hang of the other client request. To avoid the issue, make sure we have zero bytes to ignore left in the input request when sharing the input buffer with another client. CVE-2025-49178 This issue was discovered by Nils Emmerich and reported by Julian Suleder via ERNW Vulnerability Disclosure. Signed-off-by: Olivier Fourdan Reviewed-by: Peter Hutterer Part-of: --- os/io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/os/io.c b/os/io.c index 3e39c10e6f..e7b76b9cea 100644 --- a/os/io.c +++ b/os/io.c @@ -441,7 +441,7 @@ ReadRequestFromClient(ClientPtr client) */ gotnow -= needed; - if (!gotnow) + if (!gotnow && !oci->ignoreBytes) AvailableInput = oc; if (move_header) { if (client->req_len < bytes_to_int32(sizeof(xBigReq) - sizeof(xReq))) { -- GitLab