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| author | Thomas Garnier <thgarnie@google.com> | 2017-06-15 04:12:02 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-07-08 15:05:33 +0300 |
| commit | 73ac5d6a2b6ac3ae8d1e1818f3e9946f97489bc9 (patch) | |
| tree | 5d2f715c0e07a23913a64b2e42ee8cc84ce5b5e6 /arch/arm/kernel | |
| parent | 5ea0727b163cb5575e36397a12eade68a1f35f24 (diff) | |
| download | linux-73ac5d6a2b6ac3ae8d1e1818f3e9946f97489bc9.tar.xz | |
arm/syscalls: Check address limit on user-mode return
Ensure the address limit is a user-mode segment before returning to
user-mode. Otherwise a process can corrupt kernel-mode memory and
elevate privileges [1].
The set_fs function sets the TIF_SETFS flag to force a slow path on
return. In the slow path, the address limit is checked to be USER_DS if
needed.
The TIF_SETFS flag is added to _TIF_WORK_MASK shifting _TIF_SYSCALL_WORK
for arm instruction immediate support. The global work mask is too big
to used on a single instruction so adapt ret_fast_syscall.
[1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Will Drewry <wad@chromium.org>
Cc: linux-api@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Link: http://lkml.kernel.org/r/20170615011203.144108-2-thgarnie@google.com
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/entry-common.S | 9 | ||||
| -rw-r--r-- | arch/arm/kernel/signal.c | 5 |
2 files changed, 12 insertions, 2 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index eb5cd77bf1d8..e33c32d56193 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -41,7 +41,9 @@ ret_fast_syscall: UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK + bne fast_work_pending + tst r1, #_TIF_WORK_MASK bne fast_work_pending /* perform architecture specific actions before user return */ @@ -67,12 +69,15 @@ ret_fast_syscall: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 disable_irq_notrace @ disable interrupts ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK + tst r1, #_TIF_SYSCALL_WORK + bne fast_work_pending + tst r1, #_TIF_WORK_MASK beq no_work_pending UNWIND(.fnend ) ENDPROC(ret_fast_syscall) /* Slower path - fall through to work_pending */ +fast_work_pending: #endif tst r1, #_TIF_SYSCALL_WORK diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 7b8f2141427b..3a48b54c6405 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -14,6 +14,7 @@ #include <linux/uaccess.h> #include <linux/tracehook.h> #include <linux/uprobes.h> +#include <linux/syscalls.h> #include <asm/elf.h> #include <asm/cacheflush.h> @@ -571,6 +572,10 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) * Update the trace code with the current status. */ trace_hardirqs_off(); + + /* Check valid user FS if needed */ + addr_limit_user_check(); + do { if (likely(thread_flags & _TIF_NEED_RESCHED)) { schedule(); |