linux-kernel - [PATCH 3.14 32/44] signal: fix information leak in copy_siginfo_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20150814174402.607322426@linuxfoundation.org>
Date:	Fri, 14 Aug 2015 10:45:09 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Amanieu dAntras <amanieu@...il.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Russell King <rmk@....linux.org.uk>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 3.14 32/44] signal: fix information leak in copy_siginfo_from_user32

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Amanieu d'Antras <amanieu@...il.com>

commit 3c00cb5e68dc719f2fc73a33b1b230aadfcb1309 upstream.

This function can leak kernel stack data when the user siginfo_t has a
positive si_code value.  The top 16 bits of si_code descibe which fields
in the siginfo_t union are active, but they are treated inconsistently
between copy_siginfo_from_user32, copy_siginfo_to_user32 and
copy_siginfo_to_user.

copy_siginfo_from_user32 is called from rt_sigqueueinfo and
rt_tgsigqueueinfo in which the user has full control overthe top 16 bits
of si_code.

This fixes the following information leaks:
x86:   8 bytes leaked when sending a signal from a 32-bit process to
       itself. This leak grows to 16 bytes if the process uses x32.
       (si_code = __SI_CHLD)
x86:   100 bytes leaked when sending a signal from a 32-bit process to
       a 64-bit process. (si_code = -1)
sparc: 4 bytes leaked when sending a signal from a 32-bit process to a
       64-bit process. (si_code = any)

parsic and s390 have similar bugs, but they are not vulnerable because
rt_[tg]sigqueueinfo have checks that prevent sending a positive si_code
to a different process.  These bugs are also fixed for consistency.

Signed-off-by: Amanieu d'Antras <amanieu@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Russell King <rmk@....linux.org.uk>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Chris Metcalf <cmetcalf@...hip.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/kernel/signal32.c    |    2 --
 arch/mips/kernel/signal32.c     |    2 --
 arch/powerpc/kernel/signal_32.c |    2 --
 kernel/signal.c                 |    4 ++--
 4 files changed, 2 insertions(+), 8 deletions(-)

--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -193,8 +193,6 @@ int copy_siginfo_to_user32(compat_siginf
 
 int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 {
-	memset(to, 0, sizeof *to);
-
 	if (copy_from_user(to, from, __ARCH_SI_PREAMBLE_SIZE) ||
 	    copy_from_user(to->_sifields._pad,
 			   from->_sifields._pad, SI_PAD_SIZE))
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -370,8 +370,6 @@ int copy_siginfo_to_user32(compat_siginf
 
 int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 {
-	memset(to, 0, sizeof *to);
-
 	if (copy_from_user(to, from, 3*sizeof(int)) ||
 	    copy_from_user(to->_sifields._pad,
 			   from->_sifields._pad, SI_PAD_SIZE32))
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -967,8 +967,6 @@ int copy_siginfo_to_user32(struct compat
 
 int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
 {
-	memset(to, 0, sizeof *to);
-
 	if (copy_from_user(to, from, 3*sizeof(int)) ||
 	    copy_from_user(to->_sifields._pad,
 			   from->_sifields._pad, SI_PAD_SIZE32))
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3036,7 +3036,7 @@ COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo,
 			int, sig,
 			struct compat_siginfo __user *, uinfo)
 {
-	siginfo_t info;
+	siginfo_t info = {};
 	int ret = copy_siginfo_from_user32(&info, uinfo);
 	if (unlikely(ret))
 		return ret;
@@ -3082,7 +3082,7 @@ COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo
 			int, sig,
 			struct compat_siginfo __user *, uinfo)
 {
-	siginfo_t info;
+	siginfo_t info = {};
 
 	if (copy_siginfo_from_user32(&info, uinfo))
 		return -EFAULT;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/