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SubjectRe: [PATCH] lib/vsprintf.c: increase the size of the field_width variable
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On Wed, 2015-09-09 at 12:13 +0200, Maurizio Lombardi wrote:
> When printing a bitmap using the "%*pb[l]" printk format
> a 16 bit variable (field_width) is used to store the size of the bitmap.
> In some cases 16 bits are not sufficient, the variable overflows and
> printk does not work as expected.

If more than 16 bits are necessary, it couldn't work
as a single printk is limited to 1024 bytes.

> 3. Bitmap should be set, but still empty
> # cat /sys/bus/pseudo/drivers/scsi_debug/map
[]
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
[]
> @@ -384,8 +384,8 @@ struct printf_spec {
> u8 flags; /* flags to number() */
> u8 base; /* number base, 8, 10 or 16 only */
> u8 qualifier; /* number qualifier, one of 'hHlLtzZ' */
> - s16 field_width; /* width of output field */
> s16 precision; /* # of digits/chars */
> + s32 field_width; /* width of output field */
> };
>
> static noinline_for_stack

And this makes the sizeof struct printf_spec more than
8 bytes which isn't desireable on x86-32.

%*pb is meant for smallish bitmaps, not big ones.




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