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[34.85.221.182]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78fb452c471sm3599487b3.45.2025.12.18.16.23.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Dec 2025 16:23:59 -0800 (PST) From: Pasha Tatashin To: akpm@linux-foundation.org, pasha.tatashin@soleen.com, rppt@kernel.org, graf@amazon.com, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org, pratyush@kernel.org, ricardo.neri-calderon@linux.intel.com Subject: [PATCH] kho: validate preserved memory map during population Date: Thu, 18 Dec 2025 19:23:55 -0500 Message-ID: <20251219002355.3323896-1-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.52.0.322.g1dd061c0dc-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 0714D40005 X-Stat-Signature: 8cbx8p7kifytppkifyxgh4rgwg7kpr7z X-HE-Tag: 1766103840-920822 X-HE-Meta: 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 PShUL3Kz wprujs8Rk1Wmat9TduKJ6HMjmLh6AyF++QvQxtCHxR+zxfGg49O7BqplZOlhnxbP0iZw2UX641ujmnBnKJNMxtHuW/EibPT0XoHM76mJMKHck1sRG6knt52TJXbyxHb8ZvtjFg4KxqFpnyLmVBQxa3Gk5vDScSwsgCajYcJIeZEFwPws58DCjHYLeM0GUV/y7n2ggVQ1KBAJGeSKQaYv724AvEztpyUhUq6ioERXHWKc3ylAl5h1kWNLygB6Dg8QSxx3N7BF0fYgOuCkAdYRlIdydZS6UHJHdjG986HUW1Dd0b7a0MA3e2BRKQN1Y7TgUMz0Tlhp6mQN1cUN6djaLcIatNNzlES34IQEOeMbIyUaFAaOS3yYHLMXPTSnCMNinHaCbWqbUUkedPDA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: If the previous kernel enabled KHO but did not call kho_finalize() (e.g., CONFIG_LIVEUPDATE=n or userspace skipped the finalization step), the 'preserved-memory-map' property in the FDT remains empty/zero. Previously, kho_populate() would succeed regardless of the memory map's state, reserving the incoming scratch regions in memblock. However, kho_memory_init() would later fail to deserialize the empty map. By that time, the scratch regions were already registered, leading to partial initialization and subsequent list corruption (double-free) during kho_init(). Move the validation of the preserved memory map earlier into kho_populate(). If the memory map is empty/NULL: 1. Abort kho_populate() immediately with -ENOENT. 2. Do not register or reserve the incoming scratch memory, allowing the new kernel to reclaim those pages as standard free memory. 3. Leave the global 'kho_in' state uninitialized. Consequently, kho_memory_init() sees no active KHO context (kho_in.mem_chunks is NULL) and falls back to kho_reserve_scratch(), allocating fresh scratch memory as if it were a standard cold boot. Fixes: de51999e687c ("kho: allow memory preservation state updates after finalization") Reported-by: Ricardo Closes: https://lore.kernel.org/all/20251218215613.GA17304@ranerica-svr.sc.intel.com Signed-off-by: Pasha Tatashin --- kernel/liveupdate/kexec_handover.c | 36 +++++++++++++++++------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index 9dc51fab604f..96c708f753d4 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -460,10 +460,9 @@ static void __init deserialize_bitmap(unsigned int order, } } -/* Return true if memory was deserizlied */ -static bool __init kho_mem_deserialize(const void *fdt) +/* Returns head of preserved physical memory chunks pointer from FDT */ +static struct khoser_mem_chunk * __init kho_get_mem_chunks(const void *fdt) { - struct khoser_mem_chunk *chunk; const void *mem_ptr; u64 mem; int len; @@ -471,16 +470,16 @@ static bool __init kho_mem_deserialize(const void *fdt) mem_ptr = fdt_getprop(fdt, 0, PROP_PRESERVED_MEMORY_MAP, &len); if (!mem_ptr || len != sizeof(u64)) { pr_err("failed to get preserved memory bitmaps\n"); - return false; + return NULL; } mem = get_unaligned((const u64 *)mem_ptr); - chunk = mem ? phys_to_virt(mem) : NULL; - /* No preserved physical pages were passed, no deserialization */ - if (!chunk) - return false; + return mem ? phys_to_virt(mem) : NULL; +} +static void __init kho_mem_deserialize(struct khoser_mem_chunk *chunk) +{ while (chunk) { unsigned int i; @@ -489,8 +488,6 @@ static bool __init kho_mem_deserialize(const void *fdt) &chunk->bitmaps[i]); chunk = KHOSER_LOAD_PTR(chunk->hdr.next); } - - return true; } /* @@ -1253,6 +1250,7 @@ bool kho_finalized(void) struct kho_in { phys_addr_t fdt_phys; phys_addr_t scratch_phys; + struct khoser_mem_chunk *mem_chunks; struct kho_debugfs dbg; }; @@ -1434,12 +1432,10 @@ static void __init kho_release_scratch(void) void __init kho_memory_init(void) { - if (kho_in.scratch_phys) { + if (kho_in.mem_chunks) { kho_scratch = phys_to_virt(kho_in.scratch_phys); kho_release_scratch(); - - if (!kho_mem_deserialize(kho_get_fdt())) - kho_in.fdt_phys = 0; + kho_mem_deserialize(kho_in.mem_chunks); } else { kho_reserve_scratch(); } @@ -1448,8 +1444,9 @@ void __init kho_memory_init(void) void __init kho_populate(phys_addr_t fdt_phys, u64 fdt_len, phys_addr_t scratch_phys, u64 scratch_len) { - void *fdt = NULL; + struct khoser_mem_chunk *mem_chunks; struct kho_scratch *scratch = NULL; + void *fdt = NULL; int err = 0; unsigned int scratch_cnt = scratch_len / sizeof(*kho_scratch); @@ -1475,6 +1472,14 @@ void __init kho_populate(phys_addr_t fdt_phys, u64 fdt_len, goto out; } + mem_chunks = kho_get_mem_chunks(fdt); + if (!mem_chunks) { + pr_warn("setup: handover FDT (0x%llx) present but no preserved memory found\n", + fdt_phys); + err = -ENOENT; + goto out; + } + scratch = early_memremap(scratch_phys, scratch_len); if (!scratch) { pr_warn("setup: failed to memremap scratch (phys=0x%llx, len=%lld)\n", @@ -1515,6 +1520,7 @@ void __init kho_populate(phys_addr_t fdt_phys, u64 fdt_len, kho_in.fdt_phys = fdt_phys; kho_in.scratch_phys = scratch_phys; + kho_in.mem_chunks = mem_chunks; kho_scratch_cnt = scratch_cnt; pr_info("found kexec handover data.\n"); -- 2.52.0.322.g1dd061c0dc-goog