| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 073/158] MIPS: OCTEON: make get_system_type() thread-safe | Date | Mon, 15 Sep 2014 12:25:12 -0700 |
| |
3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Aaro Koskinen <aaro.koskinen@nsn.com>
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 <aaro.koskinen@nsn.com> Reviewed-by: Markos Chandras <markos.chandras@imgtec.com> Patchwork: http://patchwork.linux-mips.org/patch/7437/ Signed-off-by: James Hogan <james.hogan@imgtec.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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 @@ -458,6 +458,18 @@ 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); + /** * Return a string representing the system type * @@ -465,11 +477,7 @@ static void octeon_halt(void) */ 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)
|