vsprintf: kptr_restrict is okay in IRQ when 2 (7eb39129) · Commits · 戴 / test

The kptr_restrict flag, when set to 1, only prints the kernel address when the user has CAP_SYSLOG. When it is set to 2, the kernel address is always printed as zero. When set to 1, this needs to check whether or not we're in IRQ. However, when set to 2, this check is unneccessary, and produces confusing results in dmesg. Thus, only make sure we're not in IRQ when mode 1 is used, but not mode 2. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by:

Jason A. Donenfeld <Jason@zx2c4.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Kees Cook <keescook@chromium.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

lib/vsprintf.c

+13 −13

Original line number	Diff line number	Diff line
		@@ -1590,22 +1590,23 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		return buf;
		}
		case 'K':
		switch (kptr_restrict) {
		case 0:
		/* Always print %pK values */
		break;
		case 1: {
		const struct cred *cred;

		/*
		* %pK cannot be used in IRQ context because its test
		* for CAP_SYSLOG would be meaningless.
		* kptr_restrict==1 cannot be used in IRQ context
		* because its test for CAP_SYSLOG would be meaningless.
		*/
		if (kptr_restrict && (in_irq() \|\| in_serving_softirq() \|\|
		in_nmi())) {
		if (in_irq() \|\| in_serving_softirq() \|\| in_nmi()) {
		if (spec.field_width == -1)
		spec.field_width = default_width;
		return string(buf, end, "pK-error", spec);
		}

		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
		@@ -1615,8 +1616,7 @@ char pointer(const char fmt, char buf, char end, void *ptr,
		* leak pointer values if a binary opens a file using
		* %pK and then elevates privileges before reading it.
		*/
		const struct cred *cred = current_cred();

		cred = current_cred();
		if (!has_capability_noaudit(current, CAP_SYSLOG) \|\|
		!uid_eq(cred->euid, cred->uid) \|\|
		!gid_eq(cred->egid, cred->gid))

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