[PATCH] initramfs: Don't free a non-existent initrd

[PATCH] initramfs: Don't free a non-existent initrd

[Steven Price]

Since 54c7a8916a88 ("initramfs: free initrd memory if opening
/initrd.image fails"), the kernel has unconditionally attempted to free
the initrd even if it doesn't exist. In the non-existent case this
causes a boot-time splat if CONFIG_DEBUG_VIRTUAL is enabled due to a
call to virt_to_phys() with a NULL address.

Instead we should check that the initrd actually exists and only attempt
to free it if it does.

Fixes: 54c7a8916a88 ("initramfs: free initrd memory if opening /initrd.image fails")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 init/initramfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/initramfs.c b/init/initramfs.c
index 435a428c2af1..178130fd61c2 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -669,7 +669,7 @@ static int __init populate_rootfs(void)
 	 * If the initrd region is overlapped with crashkernel reserved region,
 	 * free only memory that is not part of crashkernel region.
 	 */
-	if (!do_retain_initrd && !kexec_free_initrd())
+	if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
 		free_initrd_mem(initrd_start, initrd_end);
 	initrd_start = 0;
 	initrd_end = 0;
-- 
2.20.1

Re: [PATCH] initramfs: Don't free a non-existent initrd

[Mike Rapoport]

On Thu, May 16, 2019 at 03:31:25PM +0100, Steven Price wrote:
> Since 54c7a8916a88 ("initramfs: free initrd memory if opening
> /initrd.image fails"), the kernel has unconditionally attempted to free
> the initrd even if it doesn't exist. In the non-existent case this
> causes a boot-time splat if CONFIG_DEBUG_VIRTUAL is enabled due to a
> call to virt_to_phys() with a NULL address.
> 
> Instead we should check that the initrd actually exists and only attempt
> to free it if it does.
> 
> Fixes: 54c7a8916a88 ("initramfs: free initrd memory if opening /initrd.image fails")
> Reported-by: Mark Rutland <mark.rutland@arm.com>
> Tested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---

Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

>  init/initramfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/init/initramfs.c b/init/initramfs.c
> index 435a428c2af1..178130fd61c2 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c
> @@ -669,7 +669,7 @@ static int __init populate_rootfs(void)
>  	 * If the initrd region is overlapped with crashkernel reserved region,
>  	 * free only memory that is not part of crashkernel region.
>  	 */
> -	if (!do_retain_initrd && !kexec_free_initrd())
> +	if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
>  		free_initrd_mem(initrd_start, initrd_end);
>  	initrd_start = 0;
>  	initrd_end = 0;
> -- 
> 2.20.1
> 

-- 
Sincerely yours,
Mike.