u-boot: fix CVE-2024-57256

An integer overflow in ext4fs_read_symlink in Das U-Boot before 2025.01-rc1
occurs for zalloc (adding one to an le32 variable) via a crafted ext4
filesystem with an inode size of 0xffffffff, resulting in a malloc of
zero and resultant memory overwrite.

https://nvd.nist.gov/vuln/detail/CVE-2024-57256

(From OE-Core rev: 534aa63726f31241e3a9d4aa70d4005fa0300133)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-bsp/u-boot/files/CVE-2024-57256.patch

@@ -0,0 +1,51 @@
+From 49cab731abe7a98db4ac16666e3b5ab3bc799282 Mon Sep 17 00:00:00 2001
+From: Richard Weinberger <richard@nod.at>
+Date: Fri, 9 Aug 2024 11:54:28 +0200
+Subject: [PATCH 3/8] ext4: Fix integer overflow in ext4fs_read_symlink()
+
+While zalloc() takes a size_t type, adding 1 to the le32 variable
+will overflow.
+A carefully crafted ext4 filesystem can exhibit an inode size of 0xffffffff
+and as consequence zalloc() will do a zero allocation.
+
+Later in the function the inode size is again used for copying data.
+So an attacker can overwrite memory.
+
+Avoid the overflow by using the __builtin_add_overflow() helper.
+
+Signed-off-by: Richard Weinberger <richard@nod.at>
+
+CVE: CVE-2024-57256
+Upstream-Status: Backport [https://source.denx.de/u-boot/u-boot/-/commit/35f75d2a46e5859138c83a75cd2f4141c5479ab9]
+Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
+---
+ fs/ext4/ext4_common.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
+index f50de7c0..a7798296 100644
+--- a/fs/ext4/ext4_common.c
++++ b/fs/ext4/ext4_common.c
+@@ -2188,13 +2188,18 @@ static char *ext4fs_read_symlink(struct ext2fs_node *node)
+ 	struct ext2fs_node *diro = node;
+ 	int status;
+ 	loff_t actread;
++	size_t alloc_size;
+ 
+ 	if (!diro->inode_read) {
+ 		status = ext4fs_read_inode(diro->data, diro->ino, &diro->inode);
+ 		if (status == 0)
+ 			return NULL;
+ 	}
+-	symlink = zalloc(le32_to_cpu(diro->inode.size) + 1);
++
++	if (__builtin_add_overflow(le32_to_cpu(diro->inode.size), 1, &alloc_size))
++		return NULL;
++
++	symlink = zalloc(alloc_size);
+ 	if (!symlink)
+ 		return NULL;
+ 
+-- 
+2.34.1
+

meta/recipes-bsp/u-boot/u-boot_2022.01.bb

@@ -13,6 +13,7 @@ SRC_URI +=       " file://0001-riscv32-Use-double-float-ABI-for-rv32.patch \
                    file://CVE-2022-2347_2.patch \
                    file://CVE-2024-57254.patch \
                    file://CVE-2024-57255.patch \
+                   file://CVE-2024-57256.patch \
                  "
 
 DEPENDS += "bc-native dtc-native python3-setuptools-native"