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authorThomas Garnier <thgarnie@google.com>2017-06-14 18:12:03 -0700
committerThomas Gleixner <tglx@linutronix.de>2017-07-08 14:05:33 +0200
commitcf7de27ab35172a9240f079477cae3146a182998 (patch)
treecd32efb78ea45ddba04b02774c5d57a3e1b6dfa2 /arch/arm64/include/asm/uaccess.h
parentarm/syscalls: Check address limit on user-mode return (diff)
downloadlinux-dev-cf7de27ab35172a9240f079477cae3146a182998.tar.xz
linux-dev-cf7de27ab35172a9240f079477cae3146a182998.zip
arm64/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. [1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990 Signed-off-by: Thomas Garnier <thgarnie@google.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: kernel-hardening@lists.openwall.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/20170615011203.144108-3-thgarnie@google.com
Diffstat (limited to '')
-rw-r--r--arch/arm64/include/asm/uaccess.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 7b8a04789cef..ced7a7c2dd41 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -45,6 +45,9 @@ static inline void set_fs(mm_segment_t fs)
{
current_thread_info()->addr_limit = fs;
+ /* On user-mode return, check fs is correct */
+ set_thread_flag(TIF_FSCHECK);
+
/*
* Enable/disable UAO so that copy_to_user() etc can access
* kernel memory with the unprivileged instructions.