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From:   Michal Suchanek <msuchanek@suse.de>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Michal Suchanek <msuchanek@suse.de>,
        Sven Schnelle <svens@linux.ibm.com>,
        Philipp Rudo <prudo@redhat.com>,
        Sasha Levin <sashal@kernel.org>, Baoquan He <bhe@redhat.com>,
        Alexander Egorenkov <egorenar@linux.ibm.com>,
        linux-s390@vger.kernel.org (open list:S390)
Subject: [PATCH 5.15 1/6] s390/kexec_file: move kernel image size check
Date:   Fri, 23 Sep 2022 19:10:29 +0200
Message-Id: <e2869bb973f6b5fe350c52e4033fb171ef64aecd.1663951201.git.msuchanek@suse.de>
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From: Sven Schnelle <svens@linux.ibm.com>

commit 277c8389386e2ccb8417afe4e36f67fc5dcd735d upstream.

In preparation of adding support for command lines with variable
sizes on s390, the check whether the new kernel image is at least HEAD_END
bytes long isn't correct. Move the check to kexec_file_add_components()
so we can get the size of the parm area and check the size there.

The '.org HEAD_END' directive can now also be removed from head.S. This
was used in the past to reserve space for the early sccb buffer, but with
commit f1d3c5323772 ("s390/boot: move sclp early buffer from fixed address
in asm to C") this is no longer required.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/s390/boot/head.S                 |  2 --
 arch/s390/include/asm/setup.h         |  1 -
 arch/s390/kernel/machine_kexec_file.c | 17 ++---------------
 3 files changed, 2 insertions(+), 18 deletions(-)

diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index 40f4cff538b8..f3a8dba7dd5d 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -383,5 +383,3 @@ SYM_DATA_START(parmarea)
 	.byte	0
 	.org	PARMAREA+__PARMAREA_SIZE
 SYM_DATA_END(parmarea)
-
-	.org	HEAD_END
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index b6606ffd85d8..121e1a8c41d7 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -11,7 +11,6 @@
 #include <linux/build_bug.h>
 
 #define PARMAREA		0x10400
-#define HEAD_END		0x11000
 
 /*
  * Machine features detected in early.c
diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
index 3459362c54ac..29a9178ff0d4 100644
--- a/arch/s390/kernel/machine_kexec_file.c
+++ b/arch/s390/kernel/machine_kexec_file.c
@@ -243,7 +243,8 @@ void *kexec_file_add_components(struct kimage *image,
 	if (ret)
 		goto out;
 
-	if (image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
+	if (image->kernel_buf_len < PARMAREA + sizeof(struct parmarea) ||
+	    image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -333,20 +334,6 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
 	return 0;
 }
 
-int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
-				  unsigned long buf_len)
-{
-	/* A kernel must be at least large enough to contain head.S. During
-	 * load memory in head.S will be accessed, e.g. to register the next
-	 * command line. If the next kernel were smaller the current kernel
-	 * will panic at load.
-	 */
-	if (buf_len < HEAD_END)
-		return -ENOEXEC;
-
-	return kexec_image_probe_default(image, buf, buf_len);
-}
-
 int arch_kimage_file_post_load_cleanup(struct kimage *image)
 {
 	vfree(image->arch.ipl_buf);
-- 
2.35.3