Re: Linux 7.0.8

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

diff --git a/Makefile b/Makefile
index a854e46c1171..a0565b83ae40 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 7
 PATCHLEVEL = 0
-SUBLEVEL = 7
+SUBLEVEL = 8
 EXTRAVERSION =
 NAME = Baby Opossum Posse
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 007a0b61856d..d41e7a8f9c85 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -998,6 +998,9 @@ struct task_struct {
 	unsigned			sched_rt_mutex:1;
 #endif
 
+	/* Save user-dumpable when mm goes away */
+	unsigned			user_dumpable:1;
+
 	/* Bit to tell TOMOYO we're in execve(): */
 	unsigned			in_execve:1;
 	unsigned			in_iowait:1;
diff --git a/kernel/exit.c b/kernel/exit.c
index 9852444627a0..e2b636961254 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -571,6 +571,7 @@ static void exit_mm(void)
 	 */
 	smp_mb__after_spinlock();
 	local_irq_disable();
+	current->user_dumpable = (get_dumpable(mm) == SUID_DUMP_USER);
 	current->mm = NULL;
 	membarrier_update_current_mm(NULL);
 	enter_lazy_tlb(mm, current);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 392ec2f75f01..0e3ab697cff5 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -272,11 +272,24 @@ static bool ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 	return ns_capable(ns, CAP_SYS_PTRACE);
 }
 
+static bool task_still_dumpable(struct task_struct *task, unsigned int mode)
+{
+	struct mm_struct *mm = task->mm;
+	if (mm) {
+		if (get_dumpable(mm) == SUID_DUMP_USER)
+			return true;
+		return ptrace_has_cap(mm->user_ns, mode);
+	}
+
+	if (task->user_dumpable)
+		return true;
+	return ptrace_has_cap(&init_user_ns, mode);
+}
+
 /* Returns 0 on success, -errno on denial. */
 static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	const struct cred *cred = current_cred(), *tcred;
-	struct mm_struct *mm;
 	kuid_t caller_uid;
 	kgid_t caller_gid;
 
@@ -337,11 +350,8 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	 * Pairs with a write barrier in commit_creds().
 	 */
 	smp_rmb();
-	mm = task->mm;
-	if (mm &&
-	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
-	     !ptrace_has_cap(mm->user_ns, mode)))
-	    return -EPERM;
+	if (!task_still_dumpable(task, mode))
+		return -EPERM;
 
 	return security_ptrace_access_check(task, mode);
 }