From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aaro Koskinen , Markos Chandras , James Hogan Subject: [PATCH 3.10 26/71] MIPS: OCTEON: make get_system_type() thread-safe Date: Mon, 15 Sep 2014 12:26:24 -0700 Message-Id: <20140915192639.578596535@linuxfoundation.org> In-Reply-To: <20140915192638.702282534@linuxfoundation.org> References: <20140915192638.702282534@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aaro Koskinen commit 608308682addfdc7b8e2aee88f0e028331d88e4d upstream. get_system_type() is not thread-safe on OCTEON. It uses static data, also more dangerous issue is that it's calling cvmx_fuse_read_byte() every time without any synchronization. Currently it's possible to get processes stuck looping forever in kernel simply by launching multiple readers of /proc/cpuinfo: (while true; do cat /proc/cpuinfo > /dev/null; done) & (while true; do cat /proc/cpuinfo > /dev/null; done) & ... Fix by initializing the system type string only once during the early boot. Signed-off-by: Aaro Koskinen Reviewed-by: Markos Chandras Patchwork: http://patchwork.linux-mips.org/patch/7437/ Signed-off-by: James Hogan Signed-off-by: Greg Kroah-Hartman --- arch/mips/cavium-octeon/setup.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) --- a/arch/mips/cavium-octeon/setup.c +++ b/arch/mips/cavium-octeon/setup.c @@ -463,6 +463,18 @@ static void octeon_halt(void) octeon_kill_core(NULL); } +static char __read_mostly octeon_system_type[80]; + +static int __init init_octeon_system_type(void) +{ + snprintf(octeon_system_type, sizeof(octeon_system_type), "%s (%s)", + cvmx_board_type_to_string(octeon_bootinfo->board_type), + octeon_model_get_string(read_c0_prid())); + + return 0; +} +early_initcall(init_octeon_system_type); + /** * Handle all the error condition interrupts that might occur. * @@ -482,11 +494,7 @@ static irqreturn_t octeon_rlm_interrupt( */ const char *octeon_board_type_string(void) { - static char name[80]; - sprintf(name, "%s (%s)", - cvmx_board_type_to_string(octeon_bootinfo->board_type), - octeon_model_get_string(read_c0_prid())); - return name; + return octeon_system_type; } const char *get_system_type(void)