AI Trajectory

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch modifies early boot memory reservation code (__init functions) by removing error checks for memblock_reserve(). These functions are executed once during kernel initialization and are completely unreachable from user-space, making them impossible to fuzz.",
  "WorthFuzzing": false
}

null

{
  "PatchDiff": "commit 2cbd48605eb0b52c10cf04340e502aa6cb21b55e\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jul 7 00:58:51 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c\nindex 7f79c9aea4a927..1629a82b9528c7 100644\n--- a/arch/powerpc/kernel/fadump.c\n+++ b/arch/powerpc/kernel/fadump.c\n@@ -154,13 +154,8 @@ void __init fadump_append_bootargs(void)\n \tif (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)\n \t\treturn;\n \n-\tif (fw_dump.param_area \u003c fw_dump.boot_mem_top) {\n-\t\tif (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {\n-\t\t\tpr_warn(\"WARNING: Can't use additional parameters area!\\n\");\n-\t\t\tfw_dump.param_area = 0;\n-\t\t\treturn;\n-\t\t}\n-\t}\n+\tif (fw_dump.param_area \u003c fw_dump.boot_mem_top)\n+\t\tmemblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE);\n \n \tappend_args = (char *)fw_dump.param_area;\n \tlen = strlen(boot_command_line);\n@@ -632,10 +627,7 @@ int __init fadump_reserve_mem(void)\n \t\t    (fw_dump.ops-\u003efadump_setup_metadata(\u0026fw_dump) \u003c 0))\n \t\t\tgoto error_out;\n \n-\t\tif (memblock_reserve(base, size)) {\n-\t\t\tpr_err(\"Failed to reserve memory!\\n\");\n-\t\t\tgoto error_out;\n-\t\t}\n+\t\tmemblock_reserve(base, size);\n \n \t\tpr_info(\"Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\\n\",\n \t\t\t(size \u003e\u003e 20), base, (memblock_phys_mem_size() \u003e\u003e 20));\ndiff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c\nindex 37073ca1e0ad3a..ba9c412f14d94b 100644\n--- a/arch/sh/kernel/machine_kexec.c\n+++ b/arch/sh/kernel/machine_kexec.c\n@@ -165,12 +165,7 @@ void __init reserve_crashkernel(void)\n \t\t\tgoto disable;\n \t\t}\n \t} else {\n-\t\tret = memblock_reserve(crashk_res.start, crash_size);\n-\t\tif (unlikely(ret \u003c 0)) {\n-\t\t\tpr_err(\"crashkernel reservation failed - \"\n-\t\t\t       \"memory is in use\\n\");\n-\t\t\tgoto disable;\n-\t\t}\n+\t\tmemblock_reserve(crashk_res.start, crash_size);\n \t}\n \n \tcrashk_res.end = crashk_res.start + crash_size - 1;\ndiff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c\nindex 46882ce79c3a4d..f9395bc632ca43 100644\n--- a/arch/x86/kernel/setup.c\n+++ b/arch/x86/kernel/setup.c\n@@ -742,11 +742,8 @@ static void __init trim_snb_memory(void)\n \t * setup_arch(), so there is no need to reserve it here.\n \t */\n \n-\tfor (i = 0; i \u003c ARRAY_SIZE(bad_pages); i++) {\n-\t\tif (memblock_reserve(bad_pages[i], PAGE_SIZE))\n-\t\t\tprintk(KERN_WARNING \"failed to reserve 0x%08lx\\n\",\n-\t\t\t       bad_pages[i]);\n-\t}\n+\tfor (i = 0; i \u003c ARRAY_SIZE(bad_pages); i++)\n+\t\tmemblock_reserve(bad_pages[i], PAGE_SIZE);\n }\n \n static void __init trim_bios_range(void)\ndiff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c\nindex f72e280363be1e..c7367b81cc36ec 100644\n--- a/arch/xtensa/kernel/setup.c\n+++ b/arch/xtensa/kernel/setup.c\n@@ -268,10 +268,10 @@ void __init init_arch(bp_tag_t *bp_start)\n  * Initialize system. Setup memory and reserve regions.\n  */\n \n-static inline int __init_memblock mem_reserve(unsigned long start,\n-\t\t\t\t\t      unsigned long end)\n+static inline void __init_memblock mem_reserve(unsigned long start,\n+\t\t\t\t\t       unsigned long end)\n {\n-\treturn memblock_reserve(start, end - start);\n+\tmemblock_reserve(start, end - start);\n }\n \n void __init setup_arch(char **cmdline_p)\n@@ -290,11 +290,12 @@ void __init setup_arch(char **cmdline_p)\n \t/* Reserve some memory regions */\n \n #ifdef CONFIG_BLK_DEV_INITRD\n-\tif (initrd_start \u003c initrd_end \u0026\u0026\n-\t    !mem_reserve(__pa(initrd_start), __pa(initrd_end)))\n+\tif (initrd_start \u003c initrd_end) {\n+\t\tmem_reserve(__pa(initrd_start), __pa(initrd_end));\n \t\tinitrd_below_start_ok = 1;\n-\telse\n+\t} else {\n \t\tinitrd_start = 0;\n+\t}\n #endif\n \n \tmem_reserve(__pa(_stext), __pa(_end));\ndiff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c\nindex cdd431027065d1..288bcf7a5b993c 100644\n--- a/drivers/firmware/efi/tpm.c\n+++ b/drivers/firmware/efi/tpm.c\n@@ -61,12 +61,7 @@ int __init efi_tpm_eventlog_init(void)\n \t}\n \n \ttbl_size = sizeof(*log_tbl) + log_tbl-\u003esize;\n-\tif (memblock_reserve(efi.tpm_log, tbl_size)) {\n-\t\tpr_err(\"TPM Event Log memblock reserve fails (0x%lx, 0x%x)\\n\",\n-\t\t       efi.tpm_log, tbl_size);\n-\t\tret = -ENOMEM;\n-\t\tgoto out;\n-\t}\n+\tmemblock_reserve(efi.tpm_log, tbl_size);\n \n \tif (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {\n \t\tpr_info(\"TPM Final Events table not present\\n\");\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch modifies early boot memory reservation code (__init functions) by removing error checks for memblock_reserve(). These functions are executed once during kernel initialization and are completely unreachable from user-space, making them impossible to fuzz.",
  "WorthFuzzing": false
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit 2cbd48605eb0b52c10cf04340e502aa6cb21b55e
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jul 7 00:58:51 2026 +0000

    syz-cluster: applied patch under review

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 7f79c9aea4a927..1629a82b9528c7 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -154,13 +154,8 @@ void __init fadump_append_bootargs(void)
 	if (!fw_dump.dump_active || !fw_dump.param_area_supported || !fw_dump.param_area)
 		return;
 
-	if (fw_dump.param_area < fw_dump.boot_mem_top) {
-		if (memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE)) {
-			pr_warn("WARNING: Can't use additional parameters area!\n");
-			fw_dump.param_area = 0;
-			return;
-		}
-	}
+	if (fw_dump.param_area < fw_dump.boot_mem_top)
+		memblock_reserve(fw_dump.param_area, COMMAND_LINE_SIZE);
 
 	append_args = (char *)fw_dump.param_area;
 	len = strlen(boot_command_line);
@@ -632,10 +627,7 @@ int __init fadump_reserve_mem(void)
 		    (fw_dump.ops->fadump_setup_metadata(&fw_dump) < 0))
 			goto error_out;
 
-		if (memblock_reserve(base, size)) {
-			pr_err("Failed to reserve memory!\n");
-			goto error_out;
-		}
+		memblock_reserve(base, size);
 
 		pr_info("Reserved %lldMB of memory at %#016llx (System RAM: %lldMB)\n",
 			(size >> 20), base, (memblock_phys_mem_size() >> 20));
diff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c
index 37073ca1e0ad3a..ba9c412f14d94b 100644
--- a/arch/sh/kernel/machine_kexec.c
+++ b/arch/sh/kernel/machine_kexec.c
@@ -165,12 +165,7 @@ void __init reserve_crashkernel(void)
 			goto disable;
 		}
 	} else {
-		ret = memblock_reserve(crashk_res.start, crash_size);
-		if (unlikely(ret < 0)) {
-			pr_err("crashkernel reservation failed - "
-			       "memory is in use\n");
-			goto disable;
-		}
+		memblock_reserve(crashk_res.start, crash_size);
 	}
 
 	crashk_res.end = crashk_res.start + crash_size - 1;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 46882ce79c3a4d..f9395bc632ca43 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -742,11 +742,8 @@ static void __init trim_snb_memory(void)
 	 * setup_arch(), so there is no need to reserve it here.
 	 */
 
-	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
-		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
-			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
-			       bad_pages[i]);
-	}
+	for (i = 0; i < ARRAY_SIZE(bad_pages); i++)
+		memblock_reserve(bad_pages[i], PAGE_SIZE);
 }
 
 static void __init trim_bios_range(void)
diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index f72e280363be1e..c7367b81cc36ec 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -268,10 +268,10 @@ void __init init_arch(bp_tag_t *bp_start)
  * Initialize system. Setup memory and reserve regions.
  */
 
-static inline int __init_memblock mem_reserve(unsigned long start,
-					      unsigned long end)
+static inline void __init_memblock mem_reserve(unsigned long start,
+					       unsigned long end)
 {
-	return memblock_reserve(start, end - start);
+	memblock_reserve(start, end - start);
 }
 
 void __init setup_arch(char **cmdline_p)
@@ -290,11 +290,12 @@ void __init setup_arch(char **cmdline_p)
 	/* Reserve some memory regions */
 
 #ifdef CONFIG_BLK_DEV_INITRD
-	if (initrd_start < initrd_end &&
-	    !mem_reserve(__pa(initrd_start), __pa(initrd_end)))
+	if (initrd_start < initrd_end) {
+		mem_reserve(__pa(initrd_start), __pa(initrd_end));
 		initrd_below_start_ok = 1;
-	else
+	} else {
 		initrd_start = 0;
+	}
 #endif
 
 	mem_reserve(__pa(_stext), __pa(_end));
diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
index cdd431027065d1..288bcf7a5b993c 100644
--- a/drivers/firmware/efi/tpm.c
+++ b/drivers/firmware/efi/tpm.c
@@ -61,12 +61,7 @@ int __init efi_tpm_eventlog_init(void)
 	}
 
 	tbl_size = sizeof(*log_tbl) + log_tbl->size;
-	if (memblock_reserve(efi.tpm_log, tbl_size)) {
-		pr_err("TPM Event Log memblock reserve fails (0x%lx, 0x%x)\n",
-		       efi.tpm_log, tbl_size);
-		ret = -ENOMEM;
-		goto out;
-	}
+	memblock_reserve(efi.tpm_log, tbl_size);
 
 	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
 		pr_info("TPM Final Events table not present\n");

gemini-3.1-pro-preview

null

null

							input: 3417
							output: 33
							thoughts: 273
						

**Analyzing a Recent Kernel Patch**

Okay, so I'm looking at this patch and it touches a few different architecture-specific files: `arch/powerpc/kernel/fadump.c`, `arch/sh/kernel/machine_kexec.c`, `arch/x86/kernel/setup.c`, `arch/xtensa/kernel/setup.c`, and `drivers/firmware/efi/tpm.c`. The core of the change seems to be removing the return value check for `memblock_reserve()`. My initial thought is, "Hmm, why is this happening?" `memblock_reserve()` is that early boot memory allocation function, right?

The code is just *deleting* the error handling, which makes me suspect that either `memblock_reserve()` *now returns void*, or the return value is effectively being ignored. I need to clarify that point. Okay, hold on... if it's *just* removing a return check, that doesn't really scream "fuzzable". These are all functions happening during the early boot process, marked with `__init`. Fuzzing this kind of thing with syzkaller is usually a no-go, since it's all happening before the OS is fully initialized and before syzkaller even starts. Plus, these changes are likely just the removal of error checks that are either never triggered, or the underlying function signature has changed.

Let's check what the current signature for `memblock_reserve` is.

{
  "Expression": "memblock_reserve\\(",
  "PathPrefix": "include/linux/memblock.h"
}

{
  "Output": "include/linux/memblock.h=129=int memblock_phys_free(phys_addr_t base, phys_addr_t size);\ninclude/linux/memblock.h:130:int __memblock_reserve(phys_addr_t base, phys_addr_t size, int nid,\ninclude/linux/memblock.h-131-\t\t       enum memblock_flags flags);\ninclude/linux/memblock.h-132-\ninclude/linux/memblock.h:133:static __always_inline int memblock_reserve(phys_addr_t base, phys_addr_t size)\ninclude/linux/memblock.h-134-{\ninclude/linux/memblock.h:135:\treturn __memblock_reserve(base, size, NUMA_NO_NODE, 0);\ninclude/linux/memblock.h-136-}\n--\ninclude/linux/memblock.h=138=static __always_inline int memblock_reserve_kern(phys_addr_t base, phys_addr_t size)\ninclude/linux/memblock.h-139-{\ninclude/linux/memblock.h:140:\treturn __memblock_reserve(base, size, NUMA_NO_NODE, MEMBLOCK_RSRV_KERN);\ninclude/linux/memblock.h-141-}\n"
}

gemini-3.1-pro-preview

null

null

							input: 4381
							output: 76
							thoughts: 347
						

**Fuzzing Analysis: memblock_reserve Removal**

Okay, so `memblock_reserve` still returns an `int`, but this patch just rips out the return value check. Hmm, is this even worth the time to fuzz? Nah, I don't think so. This is all early boot code – it's all `__init` stuff, and the patch is just ignoring the return value of `memblock_reserve()`. Fuzzing can't get to `__init` functions. Those functions are executed and freed long before user-space even thinks about starting. Plus, the changes are trivial; they aren't introducing any new logic that's even *fuzzable*.

Let me just quickly double-check that `memblock_reserve` is only called during early boot. Yep, it’s being used to reserve physical memory regions during the initial boot process. Looking at the modified functions, we have:

*   `fadump_append_bootargs` (`__init`)
*   `fadump_reserve_mem` (`__init`)
*   `reserve_crashkernel` (`__init`)
*   `trim_snb_memory` (`__init`)
*   `mem_reserve` (`__init_memblock`)
*   `efi_tpm_eventlog_init` (`__init`)

All of them are tagged as `__init` functions. So, they execute exactly once during boot, and a fuzzer running in user-space would have absolutely no way to reach them. Therefore, `WorthFuzzing=false`. The reasoning is that the patch alters early boot memory reservation code (specifically, `__init` functions) by removing error checks on `memblock_reserve()`, and because these functions are only executed during kernel initialization and are completely inaccessible from user-space, they can't be fuzzed.

Time to call `set-results`.

{
  "EnableConfigs": [],
  "FocusSymbols": [],
  "Reasoning": "The patch modifies early boot memory reservation code (__init functions) by removing error checks for memblock_reserve(). These functions are executed once during kernel initialization and are completely unreachable from user-space, making them impossible to fuzz.",
  "WorthFuzzing": false
}

{
  "EnableConfigs": null,
  "FocusSymbols": [],
  "Reasoning": "The patch modifies early boot memory reservation code (__init functions) by removing error checks for memblock_reserve(). These functions are executed once during kernel initialization and are completely unreachable from user-space, making them impossible to fuzz.",
  "WorthFuzzing": false
}