[PATCHv2 2/2] kernel/kexec: Fix IMA when allocation happens in CMA area

[Pingfan Liu]

When I tested kexec with the latest kernel, I ran into the following warning:

[   40.712410] ------------[ cut here ]------------
[   40.712576] WARNING: CPU: 2 PID: 1562 at kernel/kexec_core.c:1001 kimage_map_segment+0x144/0x198
[...]
[   40.816047] Call trace:
[   40.818498]  kimage_map_segment+0x144/0x198 (P)
[   40.823221]  ima_kexec_post_load+0x58/0xc0
[   40.827246]  __do_sys_kexec_file_load+0x29c/0x368
[...]
[   40.855423] ---[ end trace 0000000000000000 ]---

This is caused by the fact that kexec allocates the destination directly
in the CMA area. In that case, the CMA kernel address should be exported
directly to the IMA component, instead of using the vmalloc'd address.

Fixes: 07d24902977e ("kexec: enable CMA based contiguous allocation")
Signed-off-by: Pingfan Liu <piliu at redhat.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Baoquan He <bhe at redhat.com>
Cc: Alexander Graf <graf at amazon.com>
Cc: Steven Chen <chenste at linux.microsoft.com>
Cc: linux-integrity at vger.kernel.org
Cc: <stable at vger.kernel.org>
To: kexec at lists.infradead.org
---
v1 -> v2:
return page_address(page) instead of *page

 kernel/kexec_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 9a1966207041..332204204e53 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -967,6 +967,7 @@ void *kimage_map_segment(struct kimage *image, int idx)
 	kimage_entry_t *ptr, entry;
 	struct page **src_pages;
 	unsigned int npages;
+	struct page *cma;
 	void *vaddr = NULL;
 	int i;
 
@@ -974,6 +975,9 @@ void *kimage_map_segment(struct kimage *image, int idx)
 	size = image->segment[idx].memsz;
 	eaddr = addr + size;
 
+	cma = image->segment_cma[idx];
+	if (cma)
+		return page_address(cma);
 	/*
 	 * Collect the source pages and map them in a contiguous VA range.
 	 */
@@ -1014,7 +1018,8 @@ void *kimage_map_segment(struct kimage *image, int idx)
 
 void kimage_unmap_segment(void *segment_buffer)
 {
-	vunmap(segment_buffer);
+	if (is_vmalloc_addr(segment_buffer))
+		vunmap(segment_buffer);
 }
 
 struct kexec_load_limit {
-- 
2.49.0