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lib/vsprintf: Fix to check field_width and precision

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Check the field_width and presition correctly. Previously it depends
on the bitfield conversion from int to check out-of-range error.
However, commit 938df695e9 ("vsprintf: associate the format state
with the format pointer") changed those fields to int.
We need to check the out-of-range correctly without bitfield
conversion.

Fixes: 938df695e9 ("vsprintf: associate the format state with the format pointer")
Reported-by: David Laight <david.laight.linux@gmail.com>
Closes: https://lore.kernel.org/all/20260318151250.40fef0ab@pumpkin/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://patch.msgid.link/177452712047.197965.16376597502504928495.stgit@devnote2
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Masami Hiramatsu (Google)
2026-03-26 21:12:00 +09:00
committed by Petr Mladek
parent b66cb4f156
commit 71876dffab
1 changed files with 14 additions and 22 deletions
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36
lib/vsprintf.c
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@@ -2640,6 +2640,18 @@ static unsigned char spec_flag(unsigned char c)
return (c < sizeof(spec_flag_array)) ? spec_flag_array[c] : 0;
}
static void set_field_width(struct printf_spec *spec, int width)
{
spec->field_width = clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX);
WARN_ONCE(spec->field_width != width, "field width %d out of range", width);
}
static void set_precision(struct printf_spec *spec, int prec)
{
spec->precision = clamp(prec, 0, PRECISION_MAX);
WARN_ONCE(spec->precision < prec, "precision %d too large", prec);
}
/*
* Helper function to decode printf style format.
* Each call decode a token from the format and return the
@@ -2710,7 +2722,7 @@ struct fmt format_decode(struct fmt fmt, struct printf_spec *spec)
spec->field_width = -1;
if (isdigit(*fmt.str))
spec->field_width = skip_atoi(&fmt.str);
set_field_width(spec, skip_atoi(&fmt.str));
else if (unlikely(*fmt.str == '*')) {
/* it's the next argument */
fmt.state = FORMAT_STATE_WIDTH;
@@ -2724,9 +2736,7 @@ struct fmt format_decode(struct fmt fmt, struct printf_spec *spec)
if (unlikely(*fmt.str == '.')) {
fmt.str++;
if (isdigit(*fmt.str)) {
spec->precision = skip_atoi(&fmt.str);
if (spec->precision < 0)
spec->precision = 0;
set_precision(spec, skip_atoi(&fmt.str));
} else if (*fmt.str == '*') {
/* it's the next argument */
fmt.state = FORMAT_STATE_PRECISION;
@@ -2799,24 +2809,6 @@ struct fmt format_decode(struct fmt fmt, struct printf_spec *spec)
return fmt;
}
static void
set_field_width(struct printf_spec *spec, int width)
{
spec->field_width = width;
if (WARN_ONCE(spec->field_width != width, "field width %d too large", width)) {
spec->field_width = clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX);
}
}
static void
set_precision(struct printf_spec *spec, int prec)
{
spec->precision = prec;
if (WARN_ONCE(spec->precision != prec, "precision %d too large", prec)) {
spec->precision = clamp(prec, 0, PRECISION_MAX);
}
}
/*
* Turn a 1/2/4-byte value into a 64-bit one for printing: truncate
* as necessary and deal with signedness.