kernel/SOURCES/1264-buffer-overflow-in-drivers-xen-sys-hypervisor-c.patch
Andrew Lukoshko 60fd7c7780 Recreate RHEL 5.14.0-687.13.1 from CS9/upstream backports
Add the RHEL 687.13.1 backports (1253-1269) from centos-stream-9 and upstream
stable, on top of 687.12.1. RHEL now ships the smb cifs.spnego fix (CVE-2026-46243)
too.  Bump pkgrelease and specrelease to 687.13.1.
2026-06-10 22:46:23 +00:00

61 lines
1.9 KiB
Diff

From 27fdbab4221b375de54bf91919798d88520c6e28 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Fri, 27 Mar 2026 14:13:38 +0100
Subject: [PATCH] Buffer overflow in drivers/xen/sys-hypervisor.c
The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is
neither NUL terminated nor a string.
The first causes a buffer overflow as sprintf in buildid_show will
read and copy till it finds a NUL.
00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P|
00000010 b9 a8 01 42 6f 2e 32 |...Bo.2|
00000017
So use a memcpy instead of sprintf to have the correct value:
00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P|
00000010 b9 a8 01 42 |...B|
00000014
(the above have a hack to embed a zero inside and check it's
returned correctly).
This is XSA-485 / CVE-2026-31786
Fixes: 84b7625728ea ("xen: add sysfs node for hypervisor build id")
Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
diff --git a/drivers/xen/sys-hypervisor.c b/drivers/xen/sys-hypervisor.c
index b1bb01ba82f8..91923242a5ae 100644
--- a/drivers/xen/sys-hypervisor.c
+++ b/drivers/xen/sys-hypervisor.c
@@ -366,6 +366,8 @@ static ssize_t buildid_show(struct hyp_sysfs_attr *attr, char *buffer)
ret = sprintf(buffer, "<denied>");
return ret;
}
+ if (ret > PAGE_SIZE)
+ return -ENOSPC;
buildid = kmalloc(sizeof(*buildid) + ret, GFP_KERNEL);
if (!buildid)
@@ -373,8 +375,10 @@ static ssize_t buildid_show(struct hyp_sysfs_attr *attr, char *buffer)
buildid->len = ret;
ret = HYPERVISOR_xen_version(XENVER_build_id, buildid);
- if (ret > 0)
- ret = sprintf(buffer, "%s", buildid->buf);
+ if (ret > 0) {
+ /* Build id is binary, not a string. */
+ memcpy(buffer, buildid->buf, ret);
+ }
kfree(buildid);
return ret;
--
2.50.1 (Apple Git-155)