[PATCH 1/3] board: samsung: fix set_board_info() board_name buffer overflow

[PATCH 1/3] board: samsung: fix set_board_info() board_name buffer overflow

[Ngo Luong Thanh Tra]

Replace unbounded sprintf() with snprintf() using sizeof(info) as
the bound when constructing the board_name string from bdname and
bdtype. The previous call had no size limit and could overflow the
64-byte stack buffer if the concatenated string exceeded 63 bytes.

Fixes: c9c36bf56e4c ("samsung: misc: use board specific functions to set env board info")
Signed-off-by: Ngo Luong Thanh Tra <S4210155@student.rmit.edu.au>
To: u-boot@lists.denx.de
---

 board/samsung/common/misc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/board/samsung/common/misc.c b/board/samsung/common/misc.c
index c134a9d70e2..6718f607875 100644
--- a/board/samsung/common/misc.c
+++ b/board/samsung/common/misc.c
@@ -104,7 +104,7 @@ void set_board_info(void)
 	if (!bdtype)
 		bdtype = "";
 
-	sprintf(info, "%s%s", bdname, bdtype);
+	snprintf(info, sizeof(info), "%s%s", bdname, bdtype);
 	env_set("board_name", info);
 #endif
 	snprintf(info, ARRAY_SIZE(info),  "%s%x-%s%s.dtb",
-- 
2.53.0

base-commit: c704af3c8b0f37929bce8c2a4bba27d6e89919c7
branch: fix/sys-cbsize-overflow-series

[PATCH 2/3] board: toradex: fix tdx-cfg-block prompt buffer overflow

[Ngo Luong Thanh Tra]

Replace unbounded sprintf() with snprintf() using sizeof(message)
as the bound for all prompt string assignments in
get_cfgblock_interactive(), get_cfgblock_carrier_interactive(),
do_cfgblock_carrier_create() and do_cfgblock_create(). The
previous calls had no size limit and could overflow the
CONFIG_SYS_CBSIZE-sized stack buffer if SYS_CBSIZE was configured
smaller than the longest prompt string (71 bytes).

Fixes: 8b6dc5d3943c ("toradex: tdx-cfg-block: Cleanup interactive cfg block creation")
Signed-off-by: Ngo Luong Thanh Tra <S4210155@student.rmit.edu.au>
To: u-boot@lists.denx.de
---

 board/toradex/common/tdx-cfg-block.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/board/toradex/common/tdx-cfg-block.c b/board/toradex/common/tdx-cfg-block.c
index 0fc3759695f..d75a6754c68 100644
--- a/board/toradex/common/tdx-cfg-block.c
+++ b/board/toradex/common/tdx-cfg-block.c
@@ -508,7 +508,7 @@ static int get_cfgblock_interactive(void)
 			       toradex_modules[i].name);
 	}
 
-	sprintf(message, "Enter the module ID: ");
+	snprintf(message, sizeof(message), "Enter the module ID: ");
 	len = cli_readline(message);
 
 	prodid = dectoul(console_buffer, NULL);
@@ -521,7 +521,8 @@ static int get_cfgblock_interactive(void)
 
 	len = 0;
 	while (len < 4) {
-		sprintf(message, "Enter the module version (e.g. V1.1B or V1.1#26): V");
+		snprintf(message, sizeof(message),
+			 "Enter the module version (e.g. V1.1B or V1.1#26): V");
 		len = cli_readline(message);
 	}
 
@@ -535,7 +536,7 @@ static int get_cfgblock_interactive(void)
 	}
 
 	while (len < 8) {
-		sprintf(message, "Enter module serial number: ");
+		snprintf(message, sizeof(message), "Enter module serial number: ");
 		len = cli_readline(message);
 	}
 
@@ -744,12 +745,13 @@ static int get_cfgblock_carrier_interactive(void)
 		       toradex_carrier_boards[i].name,
 		       toradex_carrier_boards[i].pid4);
 
-	sprintf(message, "Choose your carrier board (provide ID): ");
+	snprintf(message, sizeof(message), "Choose your carrier board (provide ID): ");
 	len = cli_readline(message);
 	tdx_car_hw_tag.prodid = dectoul(console_buffer, NULL);
 
 	do {
-		sprintf(message, "Enter carrier board version (e.g. V1.1B or V1.1#26): V");
+		snprintf(message, sizeof(message),
+			 "Enter carrier board version (e.g. V1.1B or V1.1#26): V");
 		len = cli_readline(message);
 	} while (len < 4);
 
@@ -763,7 +765,7 @@ static int get_cfgblock_carrier_interactive(void)
 	}
 
 	while (len < 8) {
-		sprintf(message, "Enter carrier board serial number: ");
+		snprintf(message, sizeof(message), "Enter carrier board serial number: ");
 		len = cli_readline(message);
 	}
 
@@ -799,7 +801,8 @@ static int do_cfgblock_carrier_create(struct cmd_tbl *cmdtp, int flag, int argc,
 	if (valid_cfgblock_carrier && !force_overwrite) {
 		char message[CONFIG_SYS_CBSIZE];
 
-		sprintf(message, "A valid Toradex Carrier config block is present, still recreate? [y/N] ");
+		snprintf(message, sizeof(message),
+			 "A valid Toradex Carrier config block is present, still recreate? [y/N] ");
 
 		if (!cli_readline(message))
 			goto out;
@@ -907,8 +910,8 @@ static int do_cfgblock_create(struct cmd_tbl *cmdtp, int flag, int argc,
 		if (!force_overwrite) {
 			char message[CONFIG_SYS_CBSIZE];
 
-			sprintf(message,
-				"A valid Toradex config block is present, still recreate? [y/N] ");
+			snprintf(message, sizeof(message),
+				 "A valid Toradex config block is present, still recreate? [y/N] ");
 
 			if (!cli_readline(message))
 				goto out;
-- 
2.53.0

base-commit: c704af3c8b0f37929bce8c2a4bba27d6e89919c7
branch: fix/sys-cbsize-overflow-series

[PATCH 3/3] common: cli_hush: fix console_buffer overflow on boot retry

[Ngo Luong Thanh Tra]

Replace strcpy() with strlcpy() when injecting the boot retry
command into console_buffer. Add a BUILD_BUG_ON() to catch at
compile time any configuration where CONFIG_SYS_CBSIZE is smaller
than the retry command string, and use a named constant for the
command so that the size check stays in sync if the string is
ever changed.

Fixes: 657e19f8f2dd ("cli_hush: support running bootcmd on boot retry")
Signed-off-by: Ngo Luong Thanh Tra <S4210155@student.rmit.edu.au>
To: u-boot@lists.denx.de
---

 common/cli_hush.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/common/cli_hush.c b/common/cli_hush.c
index 7bd6943d3ed..6141c2959df 100644
--- a/common/cli_hush.c
+++ b/common/cli_hush.c
@@ -84,6 +84,7 @@
 #include <cli_hush.h>
 #include <command.h>        /* find_cmd */
 #include <asm/global_data.h>
+#include <linux/build_bug.h>
 #endif
 #ifndef __U_BOOT__
 #include <ctype.h>     /* isalpha, isdigit */
@@ -1029,7 +1030,10 @@ static void get_user_input(struct in_str *i)
 #  ifdef CONFIG_RESET_TO_RETRY
 	  do_reset(NULL, 0, 0, NULL);
 #  elif IS_ENABLED(CONFIG_RETRY_BOOTCMD)
-	strcpy(console_buffer, "run bootcmd\n");
+	static const char retry_cmd[] = "run bootcmd\n";
+
+	BUILD_BUG_ON(sizeof(retry_cmd) - 1 > CONFIG_SYS_CBSIZE);
+	strlcpy(console_buffer, retry_cmd, sizeof(console_buffer));
 # else
 #	error "This only works with CONFIG_RESET_TO_RETRY or CONFIG_BOOT_RETRY_COMMAND enabled"
 #  endif
-- 
2.53.0

base-commit: c704af3c8b0f37929bce8c2a4bba27d6e89919c7
branch: fix/sys-cbsize-overflow-series

Re: [PATCH 3/3] common: cli_hush: fix console_buffer overflow on boot retry

[Rasmus Villemoes]

On Sat, Mar 28 2026, Ngo Luong Thanh Tra <ngotra27101996@gmail.com> wrote:

> Replace strcpy() with strlcpy() when injecting the boot retry
> command into console_buffer. Add a BUILD_BUG_ON() to catch at
> compile time any configuration where CONFIG_SYS_CBSIZE is smaller
> than the retry command string, and use a named constant for the
> command so that the size check stays in sync if the string is
> ever changed.
>
> Fixes: 657e19f8f2dd ("cli_hush: support running bootcmd on boot retry")
> Signed-off-by: Ngo Luong Thanh Tra <S4210155@student.rmit.edu.au>
> To: u-boot@lists.denx.de
> ---
>
>  common/cli_hush.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/common/cli_hush.c b/common/cli_hush.c
> index 7bd6943d3ed..6141c2959df 100644
> --- a/common/cli_hush.c
> +++ b/common/cli_hush.c
> @@ -84,6 +84,7 @@
>  #include <cli_hush.h>
>  #include <command.h>        /* find_cmd */
>  #include <asm/global_data.h>
> +#include <linux/build_bug.h>
>  #endif
>  #ifndef __U_BOOT__
>  #include <ctype.h>     /* isalpha, isdigit */
> @@ -1029,7 +1030,10 @@ static void get_user_input(struct in_str *i)
>  #  ifdef CONFIG_RESET_TO_RETRY
>  	  do_reset(NULL, 0, 0, NULL);
>  #  elif IS_ENABLED(CONFIG_RETRY_BOOTCMD)
> -	strcpy(console_buffer, "run bootcmd\n");
> +	static const char retry_cmd[] = "run bootcmd\n";
> +
> +	BUILD_BUG_ON(sizeof(retry_cmd) - 1 > CONFIG_SYS_CBSIZE);
> +	strlcpy(console_buffer, retry_cmd, sizeof(console_buffer));

Have you compiled this?

The declaration of console_buffer in include/console.h does not include
the size, so you should get a build error like

  error: invalid application of 'sizeof' to incomplete type 'char[]'

And exactly because that declaration doesn't include the size, the -1
and the comparison to CONFIG_SYS_CBSIZE looks rather fishy.

If anything, one should start by making the size of console_buffer part
of the declaration, so that users such as here could actually do
sizeof(console_buffer), and then one should not use or need to know that
the size if defined in terms of (but not exactly equal to)
CONFIG_SYS_CBSIZE.

Also, I generally think that this whole "must use strlcpy because
safer!" is broken when everything in sight are compile-time
constants. Because the compiler knows about strcpy(), so it can optimize
a strcpy() with a literal as source into a sequence of a few immediate
stores, which is often smaller code than emitting the string literal to
.rodata.str and emitting an actual strcpy() call with all the register
save/restore that requires. It knows nothing about strlcpy().

Unfortunately, U-Boot builds with -Wno-array-bounds, so just declaring
console_buffer with its actual size is not enough to trigger a build
error with the current strcpy(). But if you want to improve stuff in
this area, do something like creating a const_strcpy() helper macro
which will enforce that

  (a) The source is a string literal
  (b) The destination is a char array of known size
  (c) Makes it a build-time error if it doesn't fit
  (d) Uses __builtin_strcpy(dst, src) to tell the compiler that this
  really is just a strcpy(), even if -fno-builtin is in effect, and let
  the compiler optimize as it sees fit - including eliminating the whole
  thing as dead stores if it sees that the destination is not actually
  used.

Something like

#define const_strcpy(d, s) ({ \
  static_assert(__same_type(d, char[]), "destination must be char array"); \
  static_assert(__same_type(s, const char[], "source must be a string literal"); \
  static_assert(sizeof(d) >= sizeof("" s ""), "source does not fit in destination"); \
  __builtin_strcpy(d, s); \
})

Rasmus