FAILED: patch "[PATCH] bootconfig: Fix integer overflow in initrd size check" failed to apply to 5.10-stable tree

PATCH New [email protected] 2 participants 5 messages Sep 16 – Sep 17 Stable branch

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[email protected]

author maintainer

2026-09-16 15:28 UTC #0 lore raw

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 7812d6dab0698001e50e8c2f901e17da3eb6f429
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026091618-used-flashbulb-70ef@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7812d6dab0698001e50e8c2f901e17da3eb6f429 Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <[email protected]>
Date: Fri, 11 Sep 2026 00:15:34 +0900
Subject: [PATCH] bootconfig: Fix integer overflow in initrd size check

Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer arithmetic:

    data = ((void *)hdr) - size;

to wrap around on 32-bit systems (or when pointer subtraction overflows). Because data wraps around, the subsequent bounds check:

if ((unsigned long)data < initrd_start)

evaluates to false, bypassing the check. The kernel then calls xbc_calc_checksum(data, size), which attempts to read 4GB of memory, hitting unmapped pages and triggering a fatal kernel page fault during early boot. Furthermore, on 64-bit systems with an initrd > 4.29 GB, an unbounded 32-bit size can similarly bypass the initrd_start check.

Fix this by:
1. Ensuring the initrd is at least large enough to contain the bootconfig footer and verifying hdr is within the initrd bounds.
2. Checking that size does not exceed XBC_DATA_MAX and does not exceed the available space between initrd_start and hdr before performing pointer subtraction.

Link https://lore.kernel.org/all/178905333479.213925.1358412668943562406.stgit@devnote2/ open here

Fixes de462e5f1071 ("bootconfig: Fix to remove bootconfig data from initrd while boot")

Cc [email protected]

Reported-by Sashiko <[email protected]>

Closes https://lore.kernel.org/all/[email protected]/ open here

Assisted-by Antigravity:gemini-3.8-flash

Signed-off-by Masami Hiramatsu (Google) <[email protected]>

Reviewed-by Sang-Heon Jeon <[email protected]>

init/main.c +15 ~~-10~~

index 2613d3f9b3ce..16749bb7a219 100644
@@ -277,7 +277,8 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 	u8 *hdr;
 	int i;
 
-	if (!initrd_end)
+	if (!initrd_end || initrd_end < initrd_start ||
+	    initrd_end - initrd_start < BOOTCONFIG_MAGIC_LEN + 8)
 		return NULL;
 
 	data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;

@@ -294,16 +295,26 @@ static void * __init get_boot_config_from_initrd(size_t *_size)
 
 found:
 	hdr = (u8 *)(data - 8);
+	if ((unsigned long)hdr < initrd_start)
+		return NULL;
+
 	size = get_unaligned_le32(hdr);
 	csum = get_unaligned_le32(hdr + 4);
 
-	data = ((void *)hdr) - size;
-	if ((unsigned long)data < initrd_start) {
-		pr_err("bootconfig size %d is greater than initrd size %ld\n",
+	if (size > XBC_DATA_MAX) {
+		pr_err("bootconfig size %u is greater than max size %d\n",
+			size, XBC_DATA_MAX);
+		return NULL;
+	}
+
+	if (size > ((unsigned long)hdr - initrd_start)) {
+		pr_err("bootconfig size %u is greater than initrd size %lu\n",
 			size, initrd_end - initrd_start);
 		return NULL;
 	}
 
+	data = ((void *)hdr) - size;
+
 	if (xbc_calc_checksum(data, size) != csum) {
 		pr_err("bootconfig checksum failed\n");
 		return NULL;

@@ -394,12 +405,6 @@ static void __init setup_boot_config(void)
 		return;
 	}
 
-	if (size >= XBC_DATA_MAX) {
-		pr_err("bootconfig size %ld greater than max size %d\n",
-			(long)size, XBC_DATA_MAX);
-		return;
-	}
-
 	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)

Sasha Levin

maintainer

2026-09-17 02:19 UTC #1 lore raw

PATCH 1/4 ns: move to_ns_common() to ns_common.h

From: Christian Brauner <[email protected]>

[ Upstream commit e3e1812f8e25ac277f5cc9249802365300c582e3 ]

Move the helper to ns_common.h where it belongs.

Reviewed-by Jan Kara <[email protected]>

Signed-off-by Christian Brauner <[email protected]>

Stable-dep-of: 7812d6dab069 ("bootconfig: Fix integer overflow in initrd size check")

Signed-off-by Sasha Levin <[email protected]>

---
 include/linux/ns_common.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

include/linux/ns_common.h +20 -0

index 5fbc4000358f1..d2b9e0b4a928f 100644
@@ -4,10 +4,30 @@
 
 struct proc_ns_operations;
 
+struct cgroup_namespace;
+struct ipc_namespace;
+struct mnt_namespace;
+struct net;
+struct pid_namespace;
+struct time_namespace;
+struct user_namespace;
+struct uts_namespace;
+
 struct ns_common {
 	atomic_long_t stashed;
 	const struct proc_ns_operations *ops;
 	unsigned int inum;
 };
 
+#define to_ns_common(__ns)                              \
+	_Generic((__ns),                                \
+		struct cgroup_namespace *: &(__ns)->ns, \
+		struct ipc_namespace *:    &(__ns)->ns, \
+		struct mnt_namespace *:    &(__ns)->ns, \
+		struct net *:              &(__ns)->ns, \
+		struct pid_namespace *:    &(__ns)->ns, \
+		struct time_namespace *:   &(__ns)->ns, \
+		struct user_namespace *:   &(__ns)->ns, \
+		struct uts_namespace *:    &(__ns)->ns)
+
 #endif

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-17 02:19 UTC #2 lore raw

PATCH 2/4 ns: uniformly initialize ns_common

From: Christian Brauner <[email protected]>

[ Upstream commit 660def10b01b248fd97255afacb7b0e305ac833a ]

No point in cargo-culting the same code across all the different types. Use one common initializer.

Reviewed-by Jan Kara <[email protected]>

Signed-off-by Christian Brauner <[email protected]>

Stable-dep-of: 7812d6dab069 ("bootconfig: Fix integer overflow in initrd size check")

Signed-off-by Sasha Levin <[email protected]>

---
 include/linux/proc_ns.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

include/linux/proc_ns.h +16 -0

index 75807ecef880f..5ea4835550823 100644
@@ -70,6 +70,22 @@ static inline int ns_alloc_inum(struct ns_common *ns)
 	return proc_alloc_inum(&ns->inum);
 }
 
+static inline int ns_common_init(struct ns_common *ns,
+				 const struct proc_ns_operations *ops,
+				 bool alloc_inum)
+{
+	if (alloc_inum) {
+		int ret;
+		ret = proc_alloc_inum(&ns->inum);
+		if (ret)
+			return ret;
+	}
+	refcount_set(&ns->count, 1);
+	ns->stashed = NULL;
+	ns->ops = ops;
+	return 0;
+}
+
 #define ns_free_inum(ns) proc_free_inum((ns)->inum)
 
 extern struct file *proc_ns_fget(int fd);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-17 02:19 UTC #3 lore raw

PATCH 3/4 init/main: read bootconfig header with get_unaligned_le32()

In reply to Sasha Levin

From: Sun Jian <[email protected]>

[ Upstream commit 499f86de4f8c34e19a57daf2b6f0cba848e91994 ]

get_boot_config_from_initrd() scans up to 3 bytes before initrd_end to handle GRUB 4-byte alignment. As a result, the bootconfig header immediately preceding the magic may be unaligned.

Read the size and checksum fields with get_unaligned_le32() instead of casting to u32 * and using le32_to_cpu(), avoiding potential unaligned access and silencing sparse "cast to restricted __le32" warnings.

Sparse warnings (gcc + C=1):
init/main.c:292:16: warning: cast to restricted __le32 init/main.c:293:16: warning: cast to restricted __le32

No functional change intended.

Link https://lkml.kernel.org/r/[email protected] open here

Signed-off-by Sun Jian <[email protected]>

Cc Ingo Molnar <[email protected]>

Cc Thomas Gleixner <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

Stable backport notes:
- Use <asm/unaligned.h>, the unaligned-access header provided by 5.10.
- Reuse and relocate the existing boot_config_checksum() implementation as xbc_calc_checksum(), and validate the checksum before trimming the initrd, as in 765b8552a200. No additional function is introduced.
- Adapt the existing xbc_init() and its callers to the explicit-size, internally owned buffer interface from bdac5c2b243f. Use the 5.10 memblock_free(__pa(...), ...) API, handle partial allocation cleanup, and initialize the parser result after removing the strlen() assignment.
- Repair the inherited ns_common_init() from b033981390f7: 5.10 has no common count field and stashed is atomic_long_t, so initialize it with atomic_long_set() and leave per-namespace reference counts alone.
- Match the size-check diagnostic context so target 7812d6dab069 applies unchanged. Its overflow and footer-bounds checks remain in the target.

These adaptations bridge the older bootconfig implementation without pulling in unrelated modern init headers or adding functions.

Stable-dep-of: 7812d6dab069 ("bootconfig: Fix integer overflow in initrd size check")

Signed-off-by Sasha Levin <[email protected]>

---
 include/linux/bootconfig.h |  2 +-
 include/linux/proc_ns.h    |  3 +-
 init/main.c                | 69 +++++++++++++++++---------------------
 lib/bootconfig.c           | 41 ++++++++++++++--------
 tools/bootconfig/main.c    |  6 ++--
 5 files changed, 62 insertions(+), 59 deletions(-)

include/linux/bootconfig.h +1 -1

index 39d2e2468c237..15c3328ad60cc 100644
@@ -222,7 +222,7 @@ static inline int __init xbc_node_compose_key(struct xbc_node *node,
 }
 
 /* XBC node initializer */
-int __init xbc_init(char *buf, const char **emsg, int *epos);
+int __init xbc_init(const char *data, size_t size, const char **emsg, int *epos);
 
 
 /* XBC cleanup data structures */

include/linux/proc_ns.h +1 -2

index 5ea4835550823..b726eafbd2584 100644
@@ -80,8 +80,7 @@ static inline int ns_common_init(struct ns_common *ns,
 		if (ret)
 			return ret;
 	}
-	refcount_set(&ns->count, 1);
-	ns->stashed = NULL;
+	atomic_long_set(&ns->stashed, 0);
 	ns->ops = ops;
 	return 0;
 }

init/main.c +30 ~~-39~~

134 lines not on this page · raw message

lib/bootconfig.c +27 ~~-14~~

86 lines not on this page · raw message

tools/bootconfig/main.c +3 -3

index 387cb91862dfc..39081b2d768f1 100644
@@ -214,7 +214,7 @@ static int load_xbc_from_initrd(int fd, char **buf)
 		return -EINVAL;
 	}
 
-	ret = xbc_init(*buf, &msg, NULL);
+	ret = xbc_init(*buf, size, &msg, NULL);
 	/* Wrong data */
 	if (ret < 0) {
 		pr_err("parse error: %s.\n", msg);

@@ -254,7 +254,7 @@ static int init_xbc_with_error(char *buf, int len)
 	if (!copy)
 		return -ENOMEM;
 
-	ret = xbc_init(buf, &msg, &pos);
+	ret = xbc_init(buf, len, &msg, &pos);
 	if (ret < 0)
 		show_xbc_error(copy, msg, pos);
 	free(copy);

@@ -367,7 +367,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	memcpy(data, buf, size);
 
 	/* Check the data format */
-	ret = xbc_init(buf, &msg, &pos);
+	ret = xbc_init(buf, size, &msg, &pos);
 	if (ret < 0) {
 		show_xbc_error(data, msg, pos);
 		free(data);

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-09-17 02:19 UTC #4 lore raw

PATCH 4/4 bootconfig: Fix integer overflow in initrd size check

In reply to Sasha Levin

From: "Masami Hiramatsu (Google)" <[email protected]>

[ Upstream commit 7812d6dab0698001e50e8c2f901e17da3eb6f429 ]

Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer arithmetic:

    data = ((void *)hdr) - size;

to wrap around on 32-bit systems (or when pointer subtraction overflows). Because data wraps around, the subsequent bounds check:

if ((unsigned long)data < initrd_start)

Link https://lore.kernel.org/all/178905333479.213925.1358412668943562406.stgit@devnote2/ open here

Fixes de462e5f1071 ("bootconfig: Fix to remove bootconfig data from initrd while boot")

Cc [email protected]

Reported-by Sashiko <[email protected]>

Closes https://lore.kernel.org/all/[email protected]/ open here

Assisted-by Antigravity:gemini-3.8-flash

Signed-off-by Masami Hiramatsu (Google) <[email protected]>

Reviewed-by Sang-Heon Jeon <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 init/main.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

init/main.c +15 ~~-10~~

index 4da396cc3af71..faf4eecda23e6 100644
@@ -281,7 +281,8 @@ static void * __init get_boot_config_from_initrd(u32 *_size)
 	u8 *hdr;
 	int i;
 
-	if (!initrd_end)
+	if (!initrd_end || initrd_end < initrd_start ||
+	    initrd_end - initrd_start < BOOTCONFIG_MAGIC_LEN + 8)
 		return NULL;
 
 	data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN;

@@ -298,16 +299,26 @@ static void * __init get_boot_config_from_initrd(u32 *_size)
 
 found:
 	hdr = (u8 *)(data - 8);
+	if ((unsigned long)hdr < initrd_start)
+		return NULL;
+
 	size = get_unaligned_le32(hdr);
 	csum = get_unaligned_le32(hdr + 4);
 
-	data = ((void *)hdr) - size;
-	if ((unsigned long)data < initrd_start) {
-		pr_err("bootconfig size %d is greater than initrd size %ld\n",
+	if (size > XBC_DATA_MAX) {
+		pr_err("bootconfig size %u is greater than max size %d\n",
+			size, XBC_DATA_MAX);
+		return NULL;
+	}
+
+	if (size > ((unsigned long)hdr - initrd_start)) {
+		pr_err("bootconfig size %u is greater than initrd size %lu\n",
 			size, initrd_end - initrd_start);
 		return NULL;
 	}
 
+	data = ((void *)hdr) - size;
+
 	if (xbc_calc_checksum(data, size) != csum) {
 		pr_err("bootconfig checksum failed\n");
 		return NULL;

@@ -398,12 +409,6 @@ static void __init setup_boot_config(const char *cmdline)
 		return;
 	}
 
-	if (size >= XBC_DATA_MAX) {
-		pr_err("bootconfig size %ld greater than max size %d\n",
-			(long)size, XBC_DATA_MAX);
-		return;
-	}
-
 	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)

Signature · 1 line

2.53.0