From: Archana Polampalli Date: Thu, 3 Jul 2025 10:23:50 +0000 (+0530) Subject: xwayland: fix CVE-2025-49176 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=17033023d679a597e31964b0fed2b2e89cdf61ec;p=thirdparty%2Fopenembedded%2Fopenembedded-core-contrib.git xwayland: fix CVE-2025-49176 A flaw was found in the Big Requests extension. The request length is multiplied by 4 before checking against the maximum allowed size, potentially causing an integer overflow and bypassing the size check. Signed-off-by: Archana Polampalli Signed-off-by: Steve Sakoman --- diff --git a/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0001.patch b/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0001.patch new file mode 100644 index 0000000000..fd3b1d936b --- /dev/null +++ b/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0001.patch @@ -0,0 +1,93 @@ +From 03731b326a80b582e48d939fe62cb1e2b10400d9 Mon Sep 17 00:00:00 2001 +From: Olivier Fourdan +Date: Mon, 7 Apr 2025 16:13:34 +0200 +Subject: [PATCH] os: Do not overflow the integer size with BigRequest +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +The BigRequest extension allows requests larger than the 16-bit length +limit. + +It uses integers for the request length and checks for the size not to +exceed the maxBigRequestSize limit, but does so after translating the +length to integer by multiplying the given size in bytes by 4. + +In doing so, it might overflow the integer size limit before actually +checking for the overflow, defeating the purpose of the test. + +To avoid the issue, make sure to check that the request size does not +overflow the maxBigRequestSize limit prior to any conversion. + +The caller Dispatch() function however expects the return value to be in +bytes, so we cannot just return the converted value in case of error, as +that would also overflow the integer size. + +To preserve the existing API, we use a negative value for the X11 error +code BadLength as the function only return positive values, 0 or -1 and +update the caller Dispatch() function to take that case into account to +return the error code to the offending client. + +CVE-2025-49176 + +This issue was discovered by Nils Emmerich and +reported by Julian Suleder via ERNW Vulnerability Disclosure. + +Signed-off-by: Olivier Fourdan +Reviewed-by: Michel Dänzer +Part-of: + +CVE: CVE-2025-49176 + +Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/xserver/-/commit/03731b326a80b582e48d939fe62cb1e2b10400d9] + +Signed-off-by: Archana Polampalli +--- + dix/dispatch.c | 9 +++++---- + os/io.c | 4 ++++ + 2 files changed, 9 insertions(+), 4 deletions(-) + +diff --git a/dix/dispatch.c b/dix/dispatch.c +index 9e98d54..20473f1 100644 +--- a/dix/dispatch.c ++++ b/dix/dispatch.c +@@ -513,9 +513,10 @@ Dispatch(void) + + /* now, finally, deal with client requests */ + result = ReadRequestFromClient(client); +- if (result <= 0) { +- if (result < 0) +- CloseDownClient(client); ++ if (result == 0) ++ break; ++ else if (result == -1) { ++ CloseDownClient(client); + break; + } + +@@ -536,7 +537,7 @@ Dispatch(void) + client->index, + client->requestBuffer); + #endif +- if (result > (maxBigRequestSize << 2)) ++ if (result < 0 || result > (maxBigRequestSize << 2)) + result = BadLength; + else { + result = XaceHookDispatch(client, client->majorOp); +diff --git a/os/io.c b/os/io.c +index 841a0ee..aeece86 100644 +--- a/os/io.c ++++ b/os/io.c +@@ -296,6 +296,10 @@ ReadRequestFromClient(ClientPtr client) + needed = get_big_req_len(request, client); + } + client->req_len = needed; ++ if (needed > MAXINT >> 2) { ++ /* Check for potential integer overflow */ ++ return -(BadLength); ++ } + needed <<= 2; /* needed is in bytes now */ + } + if (gotnow < needed) { +-- +2.40.0 diff --git a/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0002.patch b/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0002.patch new file mode 100644 index 0000000000..6d7df79111 --- /dev/null +++ b/meta/recipes-graphics/xwayland/xwayland/CVE-2025-49176-0002.patch @@ -0,0 +1,38 @@ +From 4fc4d76b2c7aaed61ed2653f997783a3714c4fe1 Mon Sep 17 00:00:00 2001 +From: Olivier Fourdan +Date: Wed, 18 Jun 2025 08:39:02 +0200 +Subject: [PATCH] os: Check for integer overflow on BigRequest length + +Check for another possible integer overflow once we get a complete xReq +with BigRequest. + +Related to CVE-2025-49176 + +Signed-off-by: Olivier Fourdan +Suggested-by: Peter Harris +Part-of: + +CVE: CVE-2025-49176 + +Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/xserver/-/commit/4fc4d76b2c7aaed61ed2653f997783a3714c4fe1] + +Signed-off-by: Archana Polampalli +--- + os/io.c | 2 ++ + 1 file changed, 2 insertions(+) + +diff --git a/os/io.c b/os/io.c +index aeece86..67465f9 100644 +--- a/os/io.c ++++ b/os/io.c +@@ -395,6 +395,8 @@ ReadRequestFromClient(ClientPtr client) + needed = get_big_req_len(request, client); + } + client->req_len = needed; ++ if (needed > MAXINT >> 2) ++ return -(BadLength); + needed <<= 2; + } + if (gotnow < needed) { +-- +2.40.0 diff --git a/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb b/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb index 55d381f868..40f010865e 100644 --- a/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb +++ b/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb @@ -44,6 +44,8 @@ SRC_URI = "https://www.x.org/archive/individual/xserver/xwayland-${PV}.tar.xz \ file://CVE-2025-26601-4.patch \ file://CVE-2022-49737.patch \ file://CVE-2025-49175.patch \ + file://CVE-2025-49176-0001.patch \ + file://CVE-2025-49176-0002.patch \ " SRC_URI[sha256sum] = "d11eeee73290b88ea8da42a7d9350dedfaba856ce4ae44e58c045ad9ecaa2f73"