Re: [PATCH] kernel/panic: increase buffer size for verbose taint logging

[Andrew Morton]

On Fri, 20 Feb 2026 20:45:00 +0530 Rio <rioo.tsukatsukii@xxxxxxxxx> wrote:

> The verbose 'Tainted: ...' string in print_tainted_seq
> can total to 327 characters while the buffer defined in
> _print_tainted is 320 bytes. Increase its size to 350
> characters to hold all flags, along with some headroom.
> 
> ...
>
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -854,10 +854,12 @@ static void print_tainted_seq(struct seq_buf *s, bool verbose)
>  	}
>  }
>  
> +/* 350 can accomadate all taint flags in verbose mode, with some headroom */

"accommodate".  I'll fix this.

> +#define TAINT_BUF_MAX 350
> +
>  static const char *_print_tainted(bool verbose)
>  {
> -	/* FIXME: what should the size be? */
> -	static char buf[sizeof(taint_flags)];

Well that was weird.

> +	static char buf[TAINT_BUF_MAX];

Can you think of a way to do this more flexibly?  Something which
scales as we add more flags?

Probably not, as it's dependent upon the length of the various
taint_flags.desc strings.


>  	struct seq_buf s;
>  
>  	BUILD_BUG_ON(ARRAY_SIZE(taint_flags) != TAINT_FLAGS_COUNT);

How does this look?

--- a/kernel/panic.c~kernel-panic-increase-buffer-size-for-verbose-taint-logging-fix
+++ a/kernel/panic.c
@@ -801,6 +801,8 @@ EXPORT_SYMBOL(panic);
  * Documentation/admin-guide/tainted-kernels.rst, including its
  * small shell script that prints the TAINT_FLAGS_COUNT bits of
  * /proc/sys/kernel/tainted.
+ *
+ * Also, update TAINT_BUF_MAX below.
  */
 const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
 	TAINT_FLAG(PROPRIETARY_MODULE,		'P', 'G'),
@@ -854,7 +856,7 @@ static void print_tainted_seq(struct seq
 	}
 }
 
-/* 350 can accomadate all taint flags in verbose mode, with some headroom */
+/* 350 can accommodate all taint flags in verbose mode, with some headroom */
 #define TAINT_BUF_MAX 350
 
 static const char *_print_tainted(bool verbose)
_