diff options
Diffstat (limited to 'meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0109-signal-Extend-exec_id-to-64bits.patch')
| -rw-r--r-- | meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0109-signal-Extend-exec_id-to-64bits.patch | 88 |
1 files changed, 0 insertions, 88 deletions
diff --git a/meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0109-signal-Extend-exec_id-to-64bits.patch b/meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0109-signal-Extend-exec_id-to-64bits.patch deleted file mode 100644 index 7d879ab82..000000000 --- a/meta-openbmc-mods/meta-common/recipes-kernel/linux/linux-aspeed/0109-signal-Extend-exec_id-to-64bits.patch +++ /dev/null @@ -1,88 +0,0 @@ -From 5f2d04139aa5ed04eab54b84e8a25bab87a2449c Mon Sep 17 00:00:00 2001 -From: "Eric W. Biederman" <ebiederm@xmission.com> -Date: Mon, 30 Mar 2020 19:01:04 -0500 -Subject: [PATCH] signal: Extend exec_id to 64bits - -commit d1e7fd6462ca9fc76650fbe6ca800e35b24267da upstream. - -Replace the 32bit exec_id with a 64bit exec_id to make it impossible -to wrap the exec_id counter. With care an attacker can cause exec_id -wrap and send arbitrary signals to a newly exec'd parent. This -bypasses the signal sending checks if the parent changes their -credentials during exec. - -The severity of this problem can been seen that in my limited testing -of a 32bit exec_id it can take as little as 19s to exec 65536 times. -Which means that it can take as little as 14 days to wrap a 32bit -exec_id. Adam Zabrocki has succeeded wrapping the self_exe_id in 7 -days. Even my slower timing is in the uptime of a typical server. -Which means self_exec_id is simply a speed bump today, and if exec -gets noticably faster self_exec_id won't even be a speed bump. - -Extending self_exec_id to 64bits introduces a problem on 32bit -architectures where reading self_exec_id is no longer atomic and can -take two read instructions. Which means that is is possible to hit -a window where the read value of exec_id does not match the written -value. So with very lucky timing after this change this still -remains expoiltable. - -I have updated the update of exec_id on exec to use WRITE_ONCE -and the read of exec_id in do_notify_parent to use READ_ONCE -to make it clear that there is no locking between these two -locations. - -Link: https://lore.kernel.org/kernel-hardening/20200324215049.GA3710@pi3.com.pl -Fixes: 2.3.23pre2 -Cc: stable@vger.kernel.org -Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - fs/exec.c | 2 +- - include/linux/sched.h | 4 ++-- - kernel/signal.c | 2 +- - 3 files changed, 4 insertions(+), 4 deletions(-) - -diff --git a/fs/exec.c b/fs/exec.c -index c27231234764..fc2870f2aca9 100644 ---- a/fs/exec.c -+++ b/fs/exec.c -@@ -1383,7 +1383,7 @@ void setup_new_exec(struct linux_binprm * bprm) - - /* An exec changes our domain. We are no longer part of the thread - group */ -- current->self_exec_id++; -+ WRITE_ONCE(current->self_exec_id, current->self_exec_id + 1); - flush_signal_handlers(current, 0); - } - EXPORT_SYMBOL(setup_new_exec); -diff --git a/include/linux/sched.h b/include/linux/sched.h -index b968d736833b..5710b80f8050 100644 ---- a/include/linux/sched.h -+++ b/include/linux/sched.h -@@ -934,8 +934,8 @@ struct task_struct { - struct seccomp seccomp; - - /* Thread group tracking: */ -- u32 parent_exec_id; -- u32 self_exec_id; -+ u64 parent_exec_id; -+ u64 self_exec_id; - - /* Protection against (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, mempolicy: */ - spinlock_t alloc_lock; -diff --git a/kernel/signal.c b/kernel/signal.c -index eea748174ade..7d3d35eb7a0b 100644 ---- a/kernel/signal.c -+++ b/kernel/signal.c -@@ -1931,7 +1931,7 @@ bool do_notify_parent(struct task_struct *tsk, int sig) - * This is only possible if parent == real_parent. - * Check if it has changed security domain. - */ -- if (tsk->parent_exec_id != tsk->parent->self_exec_id) -+ if (tsk->parent_exec_id != READ_ONCE(tsk->parent->self_exec_id)) - sig = SIGCHLD; - } - --- -2.7.4 - |