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([2602:feb4:3b:2100:742a:4153:2a1f:f028]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7482b083a9bsm1436489b3a.77.2025.06.06.09.00.33 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Jun 2025 09:00:33 -0700 (PDT) From: Steve Sakoman To: openembedded-core@lists.openembedded.org Subject: [OE-core][scarthgap 10/12] screen: fix CVE-2025-46802 Date: Fri, 6 Jun 2025 09:00:03 -0700 Message-ID: X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Fri, 06 Jun 2025 16:00:43 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-core/message/218172 From: Divya Chellam For a short time they PTY is set to mode 666, allowing any user on the system to connect to the screen session. Reference: https://security-tracker.debian.org/tracker/CVE-2025-46802 Upstream-patch: https://cgit.git.savannah.gnu.org/cgit/screen.git/commit/?id=049b26b22e197ba3be9c46e5c193032e01a4724a Signed-off-by: Divya Chellam Signed-off-by: Steve Sakoman --- .../screen/screen/CVE-2025-46802.patch | 146 ++++++++++++++++++ meta/recipes-extended/screen/screen_4.9.1.bb | 1 + 2 files changed, 147 insertions(+) create mode 100644 meta/recipes-extended/screen/screen/CVE-2025-46802.patch diff --git a/meta/recipes-extended/screen/screen/CVE-2025-46802.patch b/meta/recipes-extended/screen/screen/CVE-2025-46802.patch new file mode 100644 index 0000000000..e46affc480 --- /dev/null +++ b/meta/recipes-extended/screen/screen/CVE-2025-46802.patch @@ -0,0 +1,146 @@ +From 049b26b22e197ba3be9c46e5c193032e01a4724a Mon Sep 17 00:00:00 2001 +From: Matthias Gerstner +Date: Mon, 12 May 2025 15:15:38 +0200 +Subject: [PATCH] fix CVE-2025-46802: attacher.c - prevent temporary 0666 mode + on PTYs + +This temporary chmod of the PTY to mode 0666 is most likely a remnant of +past times, before the PTY file descriptor was passed to the target +session via the UNIX domain socket. + +This chmod() causes a race condition during which any other user in the +system can open the PTY for reading and writing, and thus allows PTY +hijacking. + +Simply remove this logic completely. + +CVE: CVE-2025-46802 + +Upstream-Status: Backport [https://cgit.git.savannah.gnu.org/cgit/screen.git/commit/?id=049b26b22e197ba3be9c46e5c193032e01a4724a] + +Signed-off-by: Divya Chellam +--- + attacher.c | 27 --------------------------- + screen.c | 19 ------------------- + 2 files changed, 46 deletions(-) + +diff --git a/attacher.c b/attacher.c +index c35ae7a..16b151e 100644 +--- a/attacher.c ++++ b/attacher.c +@@ -73,7 +73,6 @@ extern int MasterPid, attach_fd; + #ifdef MULTIUSER + extern char *multi; + extern int multiattach, multi_uid, own_uid; +-extern int tty_mode, tty_oldmode; + # ifndef USE_SETEUID + static int multipipe[2]; + # endif +@@ -160,9 +159,6 @@ int how; + + if (pipe(multipipe)) + Panic(errno, "pipe"); +- if (chmod(attach_tty, 0666)) +- Panic(errno, "chmod %s", attach_tty); +- tty_oldmode = tty_mode; + eff_uid = -1; /* make UserContext fork */ + real_uid = multi_uid; + if ((ret = UserContext()) <= 0) +@@ -174,11 +170,6 @@ int how; + Panic(errno, "UserContext"); + close(multipipe[1]); + read(multipipe[0], &dummy, 1); +- if (tty_oldmode >= 0) +- { +- chmod(attach_tty, tty_oldmode); +- tty_oldmode = -1; +- } + ret = UserStatus(); + #ifdef LOCK + if (ret == SIG_LOCK) +@@ -224,9 +215,6 @@ int how; + xseteuid(multi_uid); + xseteuid(own_uid); + #endif +- if (chmod(attach_tty, 0666)) +- Panic(errno, "chmod %s", attach_tty); +- tty_oldmode = tty_mode; + } + # endif /* USE_SETEUID */ + #endif /* MULTIUSER */ +@@ -423,13 +411,6 @@ int how; + ContinuePlease = 0; + # ifndef USE_SETEUID + close(multipipe[1]); +-# else +- xseteuid(own_uid); +- if (tty_oldmode >= 0) +- if (chmod(attach_tty, tty_oldmode)) +- Panic(errno, "chmod %s", attach_tty); +- tty_oldmode = -1; +- xseteuid(real_uid); + # endif + } + #endif +@@ -505,14 +486,6 @@ AttacherFinit SIGDEFARG + close(s); + } + } +-#ifdef MULTIUSER +- if (tty_oldmode >= 0) +- { +- if (setuid(own_uid)) +- Panic(errno, "setuid"); +- chmod(attach_tty, tty_oldmode); +- } +-#endif + exit(0); + SIGRETURN; + } +diff --git a/screen.c b/screen.c +index 7653cd1..1a23e1a 100644 +--- a/screen.c ++++ b/screen.c +@@ -230,8 +230,6 @@ char *multi_home; + int multi_uid; + int own_uid; + int multiattach; +-int tty_mode; +-int tty_oldmode = -1; + #endif + + char HostName[MAXSTR]; +@@ -1009,9 +1007,6 @@ int main(int ac, char** av) + + /* ttyname implies isatty */ + SetTtyname(true, &st); +-#ifdef MULTIUSER +- tty_mode = (int)st.st_mode & 0777; +-#endif + + fl = fcntl(0, F_GETFL, 0); + if (fl != -1 && (fl & (O_RDWR|O_RDONLY|O_WRONLY)) == O_RDWR) +@@ -2170,20 +2165,6 @@ DEFINE_VARARGS_FN(Panic) + if (D_userpid) + Kill(D_userpid, SIG_BYE); + } +-#ifdef MULTIUSER +- if (tty_oldmode >= 0) { +- +-# ifdef USE_SETEUID +- if (setuid(own_uid)) +- xseteuid(own_uid); /* may be a loop. sigh. */ +-# else +- setuid(own_uid); +-# endif +- +- debug1("Panic: changing back modes from %s\n", attach_tty); +- chmod(attach_tty, tty_oldmode); +- } +-#endif + eexit(1); + } + +-- +2.40.0 + diff --git a/meta/recipes-extended/screen/screen_4.9.1.bb b/meta/recipes-extended/screen/screen_4.9.1.bb index 96f8021255..bc4928ff77 100644 --- a/meta/recipes-extended/screen/screen_4.9.1.bb +++ b/meta/recipes-extended/screen/screen_4.9.1.bb @@ -22,6 +22,7 @@ SRC_URI = "${GNU_MIRROR}/screen/screen-${PV}.tar.gz \ file://0001-fix-for-multijob-build.patch \ file://0001-Remove-more-compatibility-stuff.patch \ file://CVE-2025-46805.patch \ + file://CVE-2025-46802.patch \ " SRC_URI[sha256sum] = "26cef3e3c42571c0d484ad6faf110c5c15091fbf872b06fa7aa4766c7405ac69"