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[122.63.73.73]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13b2abbba8dsm15858670c88.13.2026.06.30.20.04.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 20:04:46 -0700 (PDT) From: Tao Liu 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, zohar@linux.ibm.com, roberto.sassu@huawei.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, linux-integrity@vger.kernel.org, pratyush@kernel.org, Markus.Elfring@web.de, kernel-janitors@vger.kernel.org, Tao Liu Subject: [PATCH v3] riscv: Fix a NULL pointer dereference in machine_kexec_prepare Date: Wed, 1 Jul 2026 14:57:33 +1200 Message-ID: <20260701025732.66330-2-ltao@redhat.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A NULL pointer dereference 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. Fixes: b7fb4d78a6ad ("RISC-V: use memcpy for kexec_file mode") Acked-by: Baoquan He Acked-by: Pratyush Yadav Signed-off-by: Tao Liu --- v3 -> v2: Add fixes tag; Replace "reference" to "dereference". link to v2: https://lore.kernel.org/linux-riscv/20260627222602.23594-2-ltao@redhat.com/ 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