[PATCH 5/8] arm64: kexec_file: Fix CMA page leaks in segment placement retry loops

[Jinjie Ruan]

Sashiko AI code review pointed out, during kexec image placement retry
loops in image_load(), the loader attempts to find a suitable memory
hole for the kernel and its associated segments (initrd, dtb, etc.).
When a placement attempt fails midway, it restores `image->nr_segments` to
its initial state to purge failed segments.

However, this truncation causes a memory leak. Any CMA pages allocated
via kexec_add_buffer() during the failed attempt are tracked  in
the `image->segment_cma` array. Because the subsequent cleanup
kimage_free_cma() cleanup only iterates up to the truncated `nr_segments`
boundary, these allocated CMA pages outside the new boundary permanently
leaked.

Fix this by using kexec_free_segment_cma() to explicitly release the
associated CMA buffers in the failure paths before `image->nr_segments`
is reduced.

Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Breno Leitao <leitao at debian.org>
Cc: Pratyush Yadav <pratyush at kernel.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Yeoreum Yun <yeoreum.yun at arm.com>
Cc: Kees Cook <kees at kernel.org>
Cc: "Rob Herring (Arm)" <robh at kernel.org>
Cc: Baoquan He <bhe at redhat.com>
Cc: Coiby Xu <coxu at redhat.com>
Cc: Alexander Graf <graf at amazon.com>
Cc: Pasha Tatashin <pasha.tatashin at soleen.com>
Cc: stable at vger.kernel.org
Fixes: 07d24902977e4 ("kexec: enable CMA based contiguous allocation")
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 arch/arm64/kernel/kexec_image.c        | 1 +
 arch/arm64/kernel/machine_kexec_file.c | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index b70f4df15a1a..ffcb7f9075e6 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -107,6 +107,7 @@ static void *image_load(struct kimage *image,
 		 * We couldn't find space for the other segments; erase the
 		 * kernel segment and try the next available hole.
 		 */
+		kexec_free_segment_cma(image, kernel_segment_number);
 		image->nr_segments -= 1;
 		kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz;
 		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 854d872dfd0f..e48f29167b38 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -179,7 +179,10 @@ int load_other_segments(struct kimage *image,
 	return 0;
 
 out_err:
-	image->nr_segments = orig_segments;
+	while (image->nr_segments > orig_segments) {
+		kexec_free_segment_cma(image, image->nr_segments - 1);
+		image->nr_segments--;
+	}
 	kvfree(dtb);
 	return ret;
 }
-- 
2.34.1