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| author | Petr Mladek <pmladek@suse.com> | 2019-04-17 13:53:42 +0200 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2019-04-26 16:19:04 +0200 |
| commit | 1ac2f9789c4b76ad749870c25ffae0cbcd1f510f (patch) | |
| tree | 10a66ef497bf3100996fbc09cb6f231f98ac8456 /lib | |
| parent | vsprintf: Shuffle restricted_pointer() (diff) | |
| download | linux-1ac2f9789c4b76ad749870c25ffae0cbcd1f510f.tar.xz linux-1ac2f9789c4b76ad749870c25ffae0cbcd1f510f.zip | |
vsprintf: Consistent %pK handling for kptr_restrict == 0
restricted_pointer() pretends that it prints the address when kptr_restrict
is set to zero. But it is never called in this situation. Instead,
pointer() falls back to ptr_to_id() and hashes the pointer.
This patch removes the potential confusion. klp_restrict is checked only
in restricted_pointer().
It actually fixes a small race when the address might get printed unhashed:
CPU0 CPU1
pointer()
if (!kptr_restrict)
/* for example set to 2 */
restricted_pointer()
/* echo 0 >/proc/sys/kernel/kptr_restrict */
proc_dointvec_minmax_sysadmin()
klpr_restrict = 0;
switch(kptr_restrict)
case 0:
break:
number()
Fixes: ef0010a30935de4e0211 ("vsprintf: don't use 'restricted_pointer()' when not restricting")
Link: http://lkml.kernel.org/r/20190417115350.20479-3-pmladek@suse.com
To: Andy Shevchenko <andriy.shevchenko@linux.intel.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
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/vsprintf.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index eb7b4a06e1f0..2af48948a973 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -725,8 +725,8 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, { switch (kptr_restrict) { case 0: - /* Always print %pK values */ - break; + /* Handle as %p, hash and do _not_ leak addresses. */ + return ptr_to_id(buf, end, ptr, spec); case 1: { const struct cred *cred; @@ -2041,8 +2041,6 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return buf; } case 'K': - if (!kptr_restrict) - break; return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, spec, fmt); |