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vsprintf: Limit the length of inlined error messages

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The inlined error messages must be used carefully because
they need to fit into the given buffer.

Handle them using a custom wrapper that makes people aware
of the problem. Also define a reasonable hard limit to
avoid a completely insane usage.

Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Link: http://lkml.kernel.org/r/20190417115350.20479-11-pmladek@suse.com
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Tobin C . Harding" <me@tobin.cc>
Cc: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Petr Mladek 2019-04-17 13:53:50 +02:00
parent 635720ac75
commit c8c3b58434
1 changed files with 27 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
lib/vsprintf.c
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@ -612,6 +612,21 @@ static char *string_nocheck(char *buf, char *end, const char *s,
return widen_string(buf, len, end, spec);
}
/* Be careful: error messages must fit into the given buffer. */
static char *error_string(char *buf, char *end, const char *s,
struct printf_spec spec)
{
/*
* Hard limit to avoid a completely insane messages. It actually
* works pretty well because most error messages are in
* the many pointer format modifiers.
*/
if (spec.precision == -1)
spec.precision = 2 * sizeof(void *);
return string_nocheck(buf, end, s, spec);
}
/*
* This is not a fool-proof test. 99% of the time that this will fault is
* due to a bad pointer, not one that crosses into bad memory. Just test
@ -638,7 +653,7 @@ static int check_pointer(char **buf, char *end, const void *ptr,
err_msg = check_pointer_msg(ptr);
if (err_msg) {
*buf = string_nocheck(*buf, end, err_msg, spec);
*buf = error_string(*buf, end, err_msg, spec);
return -EFAULT;
}
@ -741,7 +756,7 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
if (static_branch_unlikely(&not_filled_random_ptr_key)) {
spec.field_width = 2 * sizeof(ptr);
/* string length must be less than default_width */
return string_nocheck(buf, end, str, spec);
return error_string(buf, end, str, spec);
}
#ifdef CONFIG_64BIT
@ -777,7 +792,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr,
if (in_irq() || in_serving_softirq() || in_nmi()) {
if (spec.field_width == -1)
spec.field_width = 2 * sizeof(ptr);
return string_nocheck(buf, end, "pK-error", spec);
return error_string(buf, end, "pK-error", spec);
}
/*
@ -1511,12 +1526,12 @@ char *ip_addr_string(char *buf, char *end, const void *ptr,
case AF_INET6:
return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
default:
return string_nocheck(buf, end, "(einval)", spec);
return error_string(buf, end, "(einval)", spec);
}}
}
err_fmt_msg = fmt[0] == 'i' ? "(%pi?)" : "(%pI?)";
return string_nocheck(buf, end, err_fmt_msg, spec);
return error_string(buf, end, err_fmt_msg, spec);
}
static noinline_for_stack
@ -1653,7 +1668,7 @@ char *netdev_bits(char *buf, char *end, const void *addr,
size = sizeof(netdev_features_t);
break;
default:
return string_nocheck(buf, end, "(%pN?)", spec);
return error_string(buf, end, "(%pN?)", spec);
}
return special_hex_number(buf, end, num, size);
@ -1765,7 +1780,7 @@ char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
case 'R':
return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt);
default:
return string_nocheck(buf, end, "(%ptR?)", spec);
return error_string(buf, end, "(%ptR?)", spec);
}
}
@ -1774,7 +1789,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
const char *fmt)
{
if (!IS_ENABLED(CONFIG_HAVE_CLK))
return string_nocheck(buf, end, "(%pC?)", spec);
return error_string(buf, end, "(%pC?)", spec);
if (check_pointer(&buf, end, clk, spec))
return buf;
@ -1785,7 +1800,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
#ifdef CONFIG_COMMON_CLK
return string(buf, end, __clk_get_name(clk), spec);
#else
return string_nocheck(buf, end, "(%pC?)", spec);
return error_string(buf, end, "(%pC?)", spec);
#endif
}
}
@ -1843,7 +1858,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr,
names = gfpflag_names;
break;
default:
return string_nocheck(buf, end, "(%pG?)", spec);
return error_string(buf, end, "(%pG?)", spec);
}
return format_flags(buf, end, flags, names);
@ -1899,7 +1914,7 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
str_spec.field_width = -1;
if (!IS_ENABLED(CONFIG_OF))
return string_nocheck(buf, end, "(%pOF?)", spec);
return error_string(buf, end, "(%pOF?)", spec);
if (check_pointer(&buf, end, dn, spec))
return buf;
@ -1978,7 +1993,7 @@ static char *kobject_string(char *buf, char *end, void *ptr,
return device_node_string(buf, end, ptr, spec, fmt + 1);
}
return string_nocheck(buf, end, "(%pO?)", spec);
return error_string(buf, end, "(%pO?)", spec);
}
/*