FAILED: patch "[PATCH] tools/bootconfig: Fix integer overflow and truncation in size" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] tools/bootconfig: Fix integer overflow and truncation in size" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-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 <stable@vger.kernel.org>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 462d0b066b613103f579793031429db2ca23abc0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026091615-buddhist-decimal-7a0a@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 462d0b066b613103f579793031429db2ca23abc0 Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: Fri, 11 Sep 2026 00:15:24 +0900
Subject: [PATCH] tools/bootconfig: Fix integer overflow and truncation in size
 checks

Sashiko reported that on 32-bit systems, if an attacker crafts size in
the bootconfig footer such that adding BOOTCONFIG_FOOTER_SIZE wraps around
(for instance, if size is 0xFFFFFFFF), the size check in
load_xbc_from_initrd() can be bypassed:

    if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
        pr_err("bootconfig size is too big\n");
        return -E2BIG;
    }

Furthermore, on 64-bit systems with an initrd > 4.29 GB, comparing a
corrupted 32-bit size (e.g. 0xFFFFFFFF) against
stat.st_size - BOOTCONFIG_FOOTER_SIZE can also bypass the check if
size is not bounded. Similarly, load_xbc_file() passes 64-bit stat.st_size
directly into the 32-bit int size parameter of load_xbc_fd(), truncating
large standalone files (>= 2GB).

In both cases, passing 0xFFFFFFFF to load_xbc_fd() truncates to -1,
resulting in malloc(0), an integer overflow in read(), and an
out-of-bounds null-byte write.

Fix this by:
1. Rejecting size > XBC_DATA_MAX or
   size > stat.st_size - BOOTCONFIG_FOOTER_SIZE in load_xbc_from_initrd().
2. Rejecting stat.st_size > XBC_DATA_MAX in load_xbc_file() before passing
   it to load_xbc_fd().
3. Checking size < 0 || size > XBC_DATA_MAX defensively in load_xbc_fd().

Link: https://lore.kernel.org/all/178905332413.213925.3179977110281463499.stgit@devnote2/

Fixes: 950313ebf79c ("tools: bootconfig: Add bootconfig command")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260909161113.16C691F00A3A@smtp.kernel.org/
Closes: https://lore.kernel.org/all/20260910010137.EE0431F000FF@smtp.kernel.org/
Assisted-by: Antigravity:gemini-3.8-flash
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Sang-Heon Jeon <ekffu200098@gmail.com>

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index 7dc9fff9b637..17d971d47f87 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -140,6 +140,9 @@ static int load_xbc_fd(int fd, char **buf, int size)
 {
 	int ret;
 
+	if (size < 0 || size > XBC_DATA_MAX)
+		return -EINVAL;
+
 	*buf = malloc(size + 1);
 	if (!*buf)
 		return -ENOMEM;
@@ -168,6 +171,13 @@ static int load_xbc_file(const char *path, char **buf)
 		return ret;
 	}
 
+	if (stat.st_size > XBC_DATA_MAX) {
+		pr_err("%s size is too big\n", path);
+		ret = -E2BIG;
+		close(fd);
+		return ret;
+	}
+
 	ret = load_xbc_fd(fd, buf, stat.st_size);
 
 	close(fd);
@@ -218,7 +228,8 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	csum = le32toh(csum);
 
 	/* Wrong size error  */
-	if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
+	if (size > XBC_DATA_MAX ||
+	    size > stat.st_size - BOOTCONFIG_FOOTER_SIZE) {
 		pr_err("bootconfig size is too big\n");
 		return -E2BIG;
 	}

[PATCH 6.6.y 1/2] tools/bootconfig: Cleanup bootconfig footer size calculations

[Sasha Levin]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

[ Upstream commit 26dda57695090e05c1a99c3e8f802f862d1ac474 ]

There are many same pattern of 8 + BOOTCONFIG_MAGIC_LEN for calculating
the size of bootconfig footer. Use BOOTCONFIG_FOOTER_SIZE macro to
clean up those magic numbers.

Link: https://lore.kernel.org/all/175211425693.2591046.16029516706923643510.stgit@mhiramat.tok.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Stable-dep-of: 462d0b066b61 ("tools/bootconfig: Fix integer overflow and truncation in size checks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/bootconfig/main.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index 32cf48f2da9a1..d302235f6b974 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -16,6 +16,10 @@
 
 #define pr_err(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
 
+/* Bootconfig footer is [size][csum][BOOTCONFIG_MAGIC]. */
+#define BOOTCONFIG_FOOTER_SIZE	\
+	(sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN)
+
 static int xbc_show_value(struct xbc_node *node, bool semicolon)
 {
 	const char *val, *eol;
@@ -188,7 +192,7 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	if (ret < 0)
 		return -errno;
 
-	if (stat.st_size < 8 + BOOTCONFIG_MAGIC_LEN)
+	if (stat.st_size < BOOTCONFIG_FOOTER_SIZE)
 		return 0;
 
 	if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0)
@@ -201,7 +205,7 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0)
 		return 0;
 
-	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0)
+	if (lseek(fd, -BOOTCONFIG_FOOTER_SIZE, SEEK_END) < 0)
 		return pr_errno("Failed to lseek for size", -errno);
 
 	if (read(fd, &size, sizeof(uint32_t)) < 0)
@@ -213,12 +217,12 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	csum = le32toh(csum);
 
 	/* Wrong size error  */
-	if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
+	if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
 		pr_err("bootconfig size is too big\n");
 		return -E2BIG;
 	}
 
-	if (lseek(fd, stat.st_size - (size + 8 + BOOTCONFIG_MAGIC_LEN),
+	if (lseek(fd, stat.st_size - (size + BOOTCONFIG_FOOTER_SIZE),
 		  SEEK_SET) < 0)
 		return pr_errno("Failed to lseek", -errno);
 
@@ -349,7 +353,7 @@ static int delete_xbc(const char *path)
 		ret = fstat(fd, &stat);
 		if (!ret)
 			ret = ftruncate(fd, stat.st_size
-					- size - 8 - BOOTCONFIG_MAGIC_LEN);
+					- size - BOOTCONFIG_FOOTER_SIZE);
 		if (ret)
 			ret = -errno;
 	} /* Ignore if there is no boot config in initrd */
@@ -379,8 +383,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	csum = xbc_calc_checksum(buf, size);
 
 	/* Backup the bootconfig data */
-	data = calloc(size + BOOTCONFIG_ALIGN +
-		      sizeof(uint32_t) + sizeof(uint32_t) + BOOTCONFIG_MAGIC_LEN, 1);
+	data = calloc(size + BOOTCONFIG_ALIGN + BOOTCONFIG_FOOTER_SIZE, 1);
 	if (!data)
 		return -ENOMEM;
 	memcpy(data, buf, size);
@@ -428,7 +431,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	}
 
 	/* To align up the total size to BOOTCONFIG_ALIGN, get padding size */
-	total_size = stat.st_size + size + sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN;
+	total_size = stat.st_size + size + BOOTCONFIG_FOOTER_SIZE;
 	pad = ((total_size + BOOTCONFIG_ALIGN - 1) & (~BOOTCONFIG_ALIGN_MASK)) - total_size;
 	size += pad;
 
-- 
2.53.0

[PATCH 6.6.y 2/2] tools/bootconfig: Fix integer overflow and truncation in size checks

[Sasha Levin]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

[ Upstream commit 462d0b066b613103f579793031429db2ca23abc0 ]

Sashiko reported that on 32-bit systems, if an attacker crafts size in
the bootconfig footer such that adding BOOTCONFIG_FOOTER_SIZE wraps around
(for instance, if size is 0xFFFFFFFF), the size check in
load_xbc_from_initrd() can be bypassed:

    if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
        pr_err("bootconfig size is too big\n");
        return -E2BIG;
    }

Furthermore, on 64-bit systems with an initrd > 4.29 GB, comparing a
corrupted 32-bit size (e.g. 0xFFFFFFFF) against
stat.st_size - BOOTCONFIG_FOOTER_SIZE can also bypass the check if
size is not bounded. Similarly, load_xbc_file() passes 64-bit stat.st_size
directly into the 32-bit int size parameter of load_xbc_fd(), truncating
large standalone files (>= 2GB).

In both cases, passing 0xFFFFFFFF to load_xbc_fd() truncates to -1,
resulting in malloc(0), an integer overflow in read(), and an
out-of-bounds null-byte write.

Fix this by:
1. Rejecting size > XBC_DATA_MAX or
   size > stat.st_size - BOOTCONFIG_FOOTER_SIZE in load_xbc_from_initrd().
2. Rejecting stat.st_size > XBC_DATA_MAX in load_xbc_file() before passing
   it to load_xbc_fd().
3. Checking size < 0 || size > XBC_DATA_MAX defensively in load_xbc_fd().

Link: https://lore.kernel.org/all/178905332413.213925.3179977110281463499.stgit@devnote2/

Fixes: 950313ebf79c ("tools: bootconfig: Add bootconfig command")
Cc: stable@vger.kernel.org
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/all/20260909161113.16C691F00A3A@smtp.kernel.org/
Closes: https://lore.kernel.org/all/20260910010137.EE0431F000FF@smtp.kernel.org/
Assisted-by: Antigravity:gemini-3.8-flash
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/bootconfig/main.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index d302235f6b974..655ca7da4b843 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -139,6 +139,9 @@ static int load_xbc_fd(int fd, char **buf, int size)
 {
 	int ret;
 
+	if (size < 0 || size > XBC_DATA_MAX)
+		return -EINVAL;
+
 	*buf = malloc(size + 1);
 	if (!*buf)
 		return -ENOMEM;
@@ -167,6 +170,13 @@ static int load_xbc_file(const char *path, char **buf)
 		return ret;
 	}
 
+	if (stat.st_size > XBC_DATA_MAX) {
+		pr_err("%s size is too big\n", path);
+		ret = -E2BIG;
+		close(fd);
+		return ret;
+	}
+
 	ret = load_xbc_fd(fd, buf, stat.st_size);
 
 	close(fd);
@@ -217,7 +227,8 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	csum = le32toh(csum);
 
 	/* Wrong size error  */
-	if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
+	if (size > XBC_DATA_MAX ||
+	    size > stat.st_size - BOOTCONFIG_FOOTER_SIZE) {
 		pr_err("bootconfig size is too big\n");
 		return -E2BIG;
 	}
-- 
2.53.0