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lib/vsprintf: no_hash_pointers prints all addresses as unhashed

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If the no_hash_pointers command line parameter is set, then
printk("%p") will print pointers as unhashed, which is useful for
debugging purposes.  This change applies to any function that uses
vsprintf, such as print_hex_dump() and seq_buf_printf().

A large warning message is displayed if this option is enabled.
Unhashed pointers expose kernel addresses, which can be a security
risk.

Also update test_printf to skip the hashed pointer tests if the
command-line option is set.

Signed-off-by: Timur Tabi <timur@kernel.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210214161348.369023-4-timur@kernel.org
This commit is contained in:
Timur Tabi
2021-02-14 10:13:48 -06:00
committed by Petr Mladek
parent d9d4de2309
commit 5ead723a20
3 changed files with 57 additions and 2 deletions
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8
lib/test_printf.c
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@@ -35,6 +35,8 @@ KSTM_MODULE_GLOBALS();
static char *test_buffer __initdata;
static char *alloced_buffer __initdata;
extern bool no_hash_pointers;
static int __printf(4, 0) __init
do_test(int bufsize, const char *expect, int elen,
const char *fmt, va_list ap)
@@ -301,6 +303,12 @@ plain(void)
{
int err;
if (no_hash_pointers) {
pr_warn("skipping plain 'p' tests");
skipped_tests += 2;
return;
}
err = plain_hash();
if (err) {
pr_warn("plain 'p' does not appear to be hashed\n");