From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Date: Thu, 4 Feb 2021 09:49:51 -0800
Subject: ima: Free IMA measurement buffer after kexec syscall
Git-commit: f31e3386a4e92ba6eda7328cb508462956c94c64
Patch-mainline: v5.12-rc1
References: git-fixes

IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  This buffer is not freed before
completing the kexec system call resulting in memory leak.

Add ima_buffer field in "struct kimage" to store the virtual address
of the buffer allocated for the IMA measurement list.
Free the memory allocated for the IMA measurement list in
kimage_file_post_load_cleanup() function.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 include/linux/kexec.h              |    5 +++++
 kernel/kexec_file.c                |    5 +++++
 security/integrity/ima/ima_kexec.c |    2 ++
 3 files changed, 12 insertions(+)

--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -291,6 +291,11 @@ struct kimage {
 	/* Information for loading purgatory */
 	struct purgatory_info purgatory_info;
 #endif
+
+#ifdef CONFIG_IMA_KEXEC
+	/* Virtual address of IMA measurement buffer for kexec syscall */
+	void *ima_buffer;
+#endif
 };
 
 /* kexec interface functions */
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -165,6 +165,11 @@ void kimage_file_post_load_cleanup(struc
 	vfree(pi->sechdrs);
 	pi->sechdrs = NULL;
 
+#ifdef CONFIG_IMA_KEXEC
+	vfree(image->ima_buffer);
+	image->ima_buffer = NULL;
+#endif /* CONFIG_IMA_KEXEC */
+
 	/* See if architecture has anything to cleanup post load */
 	arch_kimage_file_post_load_cleanup(image);
 
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -129,6 +129,8 @@ void ima_add_kexec_buffer(struct kimage
 		return;
 	}
 
+	image->ima_buffer = kexec_buffer;
+
 	pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
 		 kbuf.mem);
 }