From: Amanieu d'Antras <amanieu@xxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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@xxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
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(-)
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index efd1dde7094b..b9564b8d6bab 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -221,8 +221,6 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
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))
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index 57de8b751627..41f8708d21a8 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -368,8 +368,6 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
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))
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 50606e4261a1..7fce77b89f6d 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -958,8 +958,6 @@ int copy_siginfo_to_user32(struct compat_siginfo __user *d, siginfo_t *s)
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))
diff --git a/kernel/signal.c b/kernel/signal.c
index 5f558f1d3ab1..fca2decd695e 100644
--- 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;
--
2.5.0
--
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