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

[Baoquan He <bhe@redhat.com>]

Hi Pingfan,

On 11/05/25 at 09:09pm, Pingfan Liu wrote:
> 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.
> 
> Signed-off-by: Pingfan Liu <piliu@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: Alexander Graf <graf@amazon.com>
> Cc: Steven Chen <chenste@linux.microsoft.com>
> Cc: linux-integrity@vger.kernel.org
> To: kexec@lists.infradead.org
> ---
>  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..abe40286a02c 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];

Thanks for your fix. But I totally can't get what you are doing. The idx
passed into kimage_map_segment() could index image->segment[], and can
index image->segment_cma[], could you reconsider and make the code more
reasonable?

> +	if (cma)
> +		return 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
>