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From: Tao Liu <ltao@redhat.com>
To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kexec@lists.infradead.org, bhe@redhat.com,
	Tao Liu <ltao@redhat.com>
Subject: [PATCH v2] riscv: Fix a NULL pointer reference in machine_kexec_prepare
Date: Sun, 28 Jun 2026 10:26:03 +1200	[thread overview]
Message-ID: <20260627222602.23594-2-ltao@redhat.com> (raw)

A NULL pointer reference issue is noticed in riscv's machine_kexec_prepare,
where image->segment[i].buf might be NULL and copied unchecked.

The NULL buf comes from security/integrity/ima/ima_kexec.c:
ima_add_kexec_buffer(), where kbuf is added by kexec_add_buffer(),
but kbuf.buffer is NULL.

Fix this by simply adding a check before copy.

Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Tao Liu <ltao@redhat.com>
---

v2 -> v1: add code comments as suggested by Baoquan.
link to v1: https://lore.kernel.org/linux-riscv/20260529032739.13264-2-ltao@redhat.com/

---
 arch/riscv/kernel/machine_kexec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c
index 2306ce3e5f22..afc68f6a4aa1 100644
--- a/arch/riscv/kernel/machine_kexec.c
+++ b/arch/riscv/kernel/machine_kexec.c
@@ -41,6 +41,13 @@ machine_kexec_prepare(struct kimage *image)
 		if (image->segment[i].memsz <= sizeof(fdt))
 			continue;
 
+		/*
+		 * Some segments (e.g. IMA) reserve space but have no buffer
+		 * loaded yet. Skip them as they cannot contain an FDT.
+		 */
+		if (image->segment[i].buf == NULL)
+			continue;
+
 		if (image->file_mode)
 			memcpy(&fdt, image->segment[i].buf, sizeof(fdt));
 		else if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt)))
-- 
2.54.0


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WARNING: multiple messages have this Message-ID (diff)
From: Tao Liu <ltao@redhat.com>
To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kexec@lists.infradead.org, bhe@redhat.com,
	Tao Liu <ltao@redhat.com>
Subject: [PATCH v2] riscv: Fix a NULL pointer reference in machine_kexec_prepare
Date: Sun, 28 Jun 2026 10:26:03 +1200	[thread overview]
Message-ID: <20260627222602.23594-2-ltao@redhat.com> (raw)

A NULL pointer reference issue is noticed in riscv's machine_kexec_prepare,
where image->segment[i].buf might be NULL and copied unchecked.

The NULL buf comes from security/integrity/ima/ima_kexec.c:
ima_add_kexec_buffer(), where kbuf is added by kexec_add_buffer(),
but kbuf.buffer is NULL.

Fix this by simply adding a check before copy.

Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Tao Liu <ltao@redhat.com>
---

v2 -> v1: add code comments as suggested by Baoquan.
link to v1: https://lore.kernel.org/linux-riscv/20260529032739.13264-2-ltao@redhat.com/

---
 arch/riscv/kernel/machine_kexec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/riscv/kernel/machine_kexec.c b/arch/riscv/kernel/machine_kexec.c
index 2306ce3e5f22..afc68f6a4aa1 100644
--- a/arch/riscv/kernel/machine_kexec.c
+++ b/arch/riscv/kernel/machine_kexec.c
@@ -41,6 +41,13 @@ machine_kexec_prepare(struct kimage *image)
 		if (image->segment[i].memsz <= sizeof(fdt))
 			continue;
 
+		/*
+		 * Some segments (e.g. IMA) reserve space but have no buffer
+		 * loaded yet. Skip them as they cannot contain an FDT.
+		 */
+		if (image->segment[i].buf == NULL)
+			continue;
+
 		if (image->file_mode)
 			memcpy(&fdt, image->segment[i].buf, sizeof(fdt));
 		else if (copy_from_user(&fdt, image->segment[i].buf, sizeof(fdt)))
-- 
2.54.0


             reply	other threads:[~2026-06-27 22:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-27 22:26 Tao Liu [this message]
2026-06-27 22:26 ` [PATCH v2] riscv: Fix a NULL pointer reference in machine_kexec_prepare Tao Liu
2026-06-29 11:13 ` Pratyush Yadav
2026-06-29 11:13   ` Pratyush Yadav

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