linux-kernel - [PATCH] arm64: kexec: Initialize kexec_buf struct in image

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Message-Id: <20250826-akpm-v1-1-3c831f0e3799@debian.org>
Date: Tue, 26 Aug 2025 05:08:51 -0700
From: Breno Leitao <leitao@...ian.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, kexec@...ts.infradead.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 bhe@...hat.com, linux-arm-kernel@...ts.infradead.org, oxu@...hat.com, 
 berrange@...hat.com, kernel-team@...a.com, 
 Andrew Morton <akpm@...ux-foundation.org>, Breno Leitao <leitao@...ian.org>
Subject: [PATCH] arm64: kexec: Initialize kexec_buf struct in image_load()

The kexec_buf structure was previously declared without initialization
in image_load(). This led to a UBSAN warning when the structure was
expanded and uninitialized fields were accessed [1].

Zero-initializing kexec_buf at declaration ensures all fields are
cleanly set, preventing future instances of uninitialized memory being
used.

Andrew Morton suggested that this function is only called 3x a week[2],
thus, the memset() cost is inexpressive.

Link: https://lore.kernel.org/all/oninomspajhxp4omtdapxnckxydbk2nzmrix7rggmpukpnzadw@c67o7njgdgm3/ [1]
Link: https://lore.kernel.org/all/20250825180531.94bfb86a26a43127c0a1296f@linux-foundation.org/ [2]
Suggested-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 arch/arm64/kernel/kexec_image.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index 532d72ea42ee8..b70f4df15a1ae 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -41,7 +41,7 @@ static void *image_load(struct kimage *image,
 	struct arm64_image_header *h;
 	u64 flags, value;
 	bool be_image, be_kernel;
-	struct kexec_buf kbuf;
+	struct kexec_buf kbuf = {};
 	unsigned long text_offset, kernel_segment_number;
 	struct kexec_segment *kernel_segment;
 	int ret;

---
base-commit: 7a77c6b5ce68a71b9102760a988a4564ff6d4106
change-id: 20250826-akpm-18a57e3a39fd

Best regards,
--  
Breno Leitao <leitao@...ian.org>