diff options
Diffstat (limited to 'lib/vsprintf.c')
| -rw-r--r-- | lib/vsprintf.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index d74c317f4b29..ae02e421b75f 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -25,6 +25,7 @@ #include <linux/kallsyms.h> #include <linux/uaccess.h> #include <linux/ioport.h> +#include <linux/cred.h> #include <net/addrconf.h> #include <asm/page.h> /* for PAGE_SIZE */ @@ -892,10 +893,35 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, spec.field_width = 2 * sizeof(void *); return string(buf, end, "pK-error", spec); } - if (!((kptr_restrict == 0) || - (kptr_restrict == 1 && - has_capability_noaudit(current, CAP_SYSLOG)))) + + switch (kptr_restrict) { + case 0: + /* Always print %pK values */ + break; + case 1: { + /* + * Only print the real pointer value if the current + * process has CAP_SYSLOG and is running with the + * same credentials it started with. This is because + * access to files is checked at open() time, but %pK + * checks permission at read() time. We don't want to + * leak pointer values if a binary opens a file using + * %pK and then elevates privileges before reading it. + */ + const struct cred *cred = current_cred(); + + if (!has_capability_noaudit(current, CAP_SYSLOG) || + cred->euid != cred->uid || + cred->egid != cred->gid) + ptr = NULL; + break; + } + case 2: + default: + /* Always print 0's for %pK */ ptr = NULL; + break; + } break; } spec.flags |= SMALL; |