ANDROID: sprintf breaks on 4GB systemsHEADmaster

Removed all uses of sprintf from the android boot flow and replaced them
with a hex to ascii helper function.

This error is likely due to heap corruption on 4Gig 32bit systems.

Bug: 166816998
Bug: 169336575
Test: Local boot of cuttlefish & acloud
[rammuthiah: Updated change to build post v2020.10 merge]
Signed-off-by: Ram Muthiah <rammuthiah@google.com>
Change-Id: Ie986dea24c8e65736e4132321fb692e460934ef7

1 files changed, 30 insertions, 3 deletions

diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
index 6973e0b08a..b30df08f07 100644
--- a/arch/x86/lib/zimage.c
+++ b/arch/x86/lib/zimage.c
@@ -350,6 +350,33 @@ int do_zboot(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 }
 
 #ifdef CONFIG_ANDROID_BOOT_IMAGE
+static char hex_to_char(uint8_t nibble) {
+	if (nibble < 10) {
+		return '0' + nibble;
+	} else {
+		return 'a' + nibble - 10;
+	}
+}
+// Helper function to convert 32bit int to a hex string
+static void hex_to_str(char* str, ulong input) {
+	str[0] = '0'; str[1] = 'x';
+	size_t str_idx = 2;
+	uint32_t byte_extracted;
+	uint8_t nibble;
+        // Assume that this is on a little endian system.
+	for(int byte_idx = 3; byte_idx >= 0; byte_idx--) {
+		byte_extracted = ((0xFF << (byte_idx*8)) & input) >> (byte_idx*8);
+		nibble = byte_extracted & 0xF0;
+		nibble = nibble >> 4;
+		nibble = nibble & 0xF;
+		str[str_idx] = hex_to_char(nibble);
+		str_idx++;
+		nibble = byte_extracted & 0xF;
+		str[str_idx] = hex_to_char(nibble);
+		str_idx++;
+	}
+	str[str_idx] = 0;
+}
 int android_bootloader_boot_kernel(const struct andr_boot_info *boot_info)
 {
 	ulong kernel_address;
@@ -364,9 +391,9 @@ int android_bootloader_boot_kernel(const struct andr_boot_info *boot_info)
 		return -1;
 
 	kernel_address = android_image_get_kload(boot_info);
-	sprintf(kernel_addr_str, "0x%lx", kernel_address);
-	sprintf(ramdisk_addr_str, "0x%lx", ramdisk_address);
-	sprintf(ramdisk_len_str, "0x%lx", ramdisk_len);
+	hex_to_str(kernel_addr_str, kernel_address);
+	hex_to_str(ramdisk_addr_str, ramdisk_address);
+	hex_to_str(ramdisk_len_str , ramdisk_len);
 
 	printf("Booting kernel at %s with fdt at %s ramdisk %s (%s bytes)...\n\n\n",
 		kernel_addr_str, env_get("fdtaddr"), ramdisk_addr_str, ramdisk_len_str);