[PATCH v11 7/9] ima: verify if the segment size has changed

[steven chen]

kexec 'load' may be called multiple times. Free and realloc the buffer
only if the segment_size is changed from the previous kexec 'load' call.

Signed-off-by: steven chen <chen...@linux.microsoft.com>
---
 security/integrity/ima/ima_kexec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/security/integrity/ima/ima_kexec.c 
b/security/integrity/ima/ima_kexec.c
index 5c3b3e0b2186..ed867734ee70 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -33,6 +33,14 @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
 
 static int ima_alloc_kexec_file_buf(size_t segment_size)
 {
+       /*
+        * kexec 'load' may be called multiple times.
+        * Free and realloc the buffer only if the segment_size is
+        * changed from the previous kexec 'load' call.
+        */
+       if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
+               goto out;
+
        ima_free_kexec_file_buf(&ima_kexec_file);
 
        /* segment size can't change between kexec load and execute */
@@ -41,6 +49,8 @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
                return -ENOMEM;
 
        ima_kexec_file.size = segment_size;
+
+out:
        ima_kexec_file.read_pos = 0;
        ima_kexec_file.count = sizeof(struct ima_kexec_hdr);    /* reserved 
space */
 
-- 
2.25.1